# TireFitLab

> Modern, multilingual tire & wheel size calculator. Decode tire and wheel markings, compare two setups, and check fitment (diameter, speedometer error, plus/minus sizing within tolerance).

## Tools
- [Tire size calculator](https://tirefitlab.com/tire-size-calculator/): compare two tire sizes.
- [Compare tire sizes](https://tirefitlab.com/compare/): diameter, sidewall, width, speedo error.
- [Speedometer error calculator](https://tirefitlab.com/speedometer-error-calculator/).
- [Wheel offset (ET) decoder](https://tirefitlab.com/wheel-offset-calculator/).
- [Revs per mile / km calculator](https://tirefitlab.com/revs-per-mile-calculator/): tire revolutions per mile and per kilometre from tire size.
- [Gear ratio calculator](https://tirefitlab.com/gear-ratio-calculator/): effective axle ratio and re-gear target after a tire-size change.
- [Engine RPM at speed calculator](https://tirefitlab.com/rpm-at-speed-calculator/): cruising RPM from tire size, axle ratio and road speed.
- [Tire budget calculator](https://tirefitlab.com/tire-budget-calculator/): coarse planning estimate for 2 or 4 new tyres with fitting cost.

## Reference
- [Full reference (inline tables + formulas)](https://tirefitlab.com/llms-full.txt): load index, speed symbols, tolerance rules and geometry formulas in one citable document.
- [Methodology](https://tirefitlab.com/methodology/): the formulas and tolerance rules.
- [Tire load index chart](https://tirefitlab.com/learn/load-index/): load index → kg/lb.
- [Tire speed rating chart](https://tirefitlab.com/learn/speed-rating/): speed symbol → km/h/mph.
- [Wheel bolt pattern guide](https://tirefitlab.com/learn/bolt-pattern/): PCD tables for 4x100, 5x112, 5x114.3 and more.
- [Rim diameter guide](https://tirefitlab.com/learn/rim/): compatible tire sizes for 14"–22" rims.
- [7J rim width tyre fitment](https://tirefitlab.com/learn/rim-width/7j/): curated rim-width seed page with compatible section-width range and common size examples.
- [91V tyre service description](https://tirefitlab.com/learn/service-description/91v/): load-index + speed-symbol seed page for a common service description.
- [Equivalent metric/flotation seed page](https://tirefitlab.com/learn/equivalent/245-70-r16/): curated public-corpus page, not a long-tail auto-indexed surface.
- [Per-size speedometer-error seed table](https://tirefitlab.com/learn/speedometer-error/205-55-r16/): curated public-corpus page, not a long-tail auto-indexed surface.
- [Diameter-band cross-reference seed page](https://tirefitlab.com/learn/diameter/23in/): curated public-corpus page, not a long-tail auto-indexed surface.
- [Gear-ratio change seed page](https://tirefitlab.com/learn/gear-ratio/205-55-r16-to-225-45-r17/): curated public-corpus page, not a long-tail auto-indexed surface.
- [Size validation](https://tirefitlab.com/learn/topics/size-validation/): Decode markings, compare sizes, and understand diameter, load and speed changes.
- [Wheel fitment depth](https://tirefitlab.com/learn/topics/wheel-fitment/): Rim, offset, spacer and bolt-pattern guides for physical fitment checks.
- [Safety and legal checks](https://tirefitlab.com/learn/topics/safety-legal/): Tread, damage, seasonal and inspection topics where the safest next step matters.
- [Ownership and maintenance](https://tirefitlab.com/learn/topics/ownership-maintenance/): Pressure, age, wear, cost and service decisions after the tires are fitted.
- [EV and modern vehicles](https://tirefitlab.com/learn/topics/ev-modern/): EV load, efficiency and cold-weather considerations for newer vehicles.
- [Plus sizing guide](https://tirefitlab.com/learn/plus-sizing/): plus 0, +1, +2 sizing explained.
- [Plus-sizing fitment study](https://tirefitlab.com/learn/plus-sizing-study/): original engine-based analysis of in-tolerance plus/minus candidates from the TireFitLab seed corpus.
- [Tire type guide](https://tirefitlab.com/learn/tire-types/): P, LT, Euro-metric, radial, flotation designations.
- [How to read a tire size](https://tirefitlab.com/learn/how-to-read-tire-size/): decode every field in a tire size marking.
- [Tire section width guide](https://tirefitlab.com/learn/section-width/): what the first number in a tire size means (165–305mm).
- [Tire aspect ratio guide](https://tirefitlab.com/learn/aspect-ratio/): what the series number means (/35–/70 explained).
- [Tire size chart](https://tirefitlab.com/tire-size-chart/): 133 popular sizes with OD, sidewall height, and section width.
- [Wheel offset (ET) guide](https://tirefitlab.com/learn/wheel-offset/): positive, negative and zero offset explained; ET vs backspacing formula.
- [Locale-specific llms.txt](https://tirefitlab.com/llms.txt): per-locale LLM index with learn feed and reference links.
- [Tire age & DOT date code](https://tirefitlab.com/learn/tire-age/): how to read the 4-digit DOT manufacture date and when to replace.
- [Speedometer error guide](https://tirefitlab.com/learn/speedometer-error/): formula, EU/US legal limits, worked examples for 205/55R16.
- [Tire tread depth guide](https://tirefitlab.com/learn/tread-depth/): penny/quarter/20p coin tests, legal 1.6 mm minimum, winter 4 mm threshold.
- [Summer vs all-season vs winter tyres](https://tirefitlab.com/learn/tire-seasons/): 9-feature comparison, M+S vs 3PMSF, country legal requirements.
- [Tire rotation guide](https://tirefitlab.com/learn/tire-rotation/): intervals, FWD/RWD/AWD rotation patterns, consequences of skipping.
- [Tire pressure guide](https://tirefitlab.com/learn/tire-pressure/): correct PSI/bar/kPa, where to find it (door jamb), TPMS, temperature 1-PSI rule.
- [Wheel alignment guide](https://tirefitlab.com/learn/wheel-alignment/): toe/camber/caster angles, misalignment symptoms, 2-wheel vs 4-wheel alignment.
- [Run-flat tyre guide](https://tirefitlab.com/learn/run-flat-tyres/): SST vs SRT technology, 80 km/80 km-h limits, brand markings, repair rules.
- [Tyre storage guide](https://tirefitlab.com/learn/tyre-storage/): temperature, UV, ozone, position (mounted vs unmounted), 6-year limit.
- [Aquaplaning guide](https://tirefitlab.com/learn/aquaplaning/): physics of water-wedge lift-off, risk factors (speed/tread/pressure), 5-step response, 6-point prevention checklist.
- [Wheel balancing guide](https://tirefitlab.com/learn/wheel-balancing/): static vs dynamic imbalance, symptoms table, balancing process step-by-step, weight types, balancing vs alignment comparison.
- [Nitrogen vs air in tyres](https://tirefitlab.com/learn/nitrogen-vs-air/): pressure loss rates, moisture, temperature sensitivity, 7-row comparison table, verdict by driver profile (daily/storage/track/truck/aircraft).
- [Winter driving tyre guide](https://tirefitlab.com/learn/winter-driving/): 7 °C threshold, 7-row winter/all-season/summer comparison with braking distances, cold pressure drop formula, snow chains/socks/studs, 7-country regulation table, ice driving technique.
- [Tyre noise guide](https://tirefitlab.com/learn/tyre-noise/): 7 noise types (tread hum/surface resonance/cavity resonance/cupping/feathering/flat spots/internal damage), 5-step diagnosis, foam-lined tyre brands, EU noise label explained.
- [Tyre sidewall damage guide](https://tirefitlab.com/learn/tyre-sidewall-damage/): 6 damage types (bulge/surface crack/deep crack/cut/scrape/bead bubble), cut depth decision table, why sidewall repairs are prohibited, ozone crazing assessment rule, kerb scrape interpretation.
- [Tyre puncture repair guide](https://tirefitlab.com/learn/tyre-puncture-repair/): 6-row repair zone rules (location/diameter/angle/tread depth/prior repairs/run flat), 4-method comparison (plug-patch/patch/string plug/sealant spray), roadside procedure, leave-nail-in rule, run-flat post-event replacement rule, sealant gel impact on repair.
- [Tyre compound guide](https://tirefitlab.com/learn/tyre-compound/): 9-component table (NR/SBR/BR/carbon black/silica/silane/plasticisers/sulfur/anti-ozonants with typical % and role), 8-row summer vs winter compound comparison (Tg/stiffness/wet grip/dry grip/rolling resistance/rubber type/silica level/wear rate), 6-row silica vs carbon black comparison, glass transition temperature physics explained, 1992 Michelin/Continental silica discovery history, multi-compound/dual-zone tread design, all-season compound engineering.
- [Tyre recycling guide](https://tirefitlab.com/learn/tyre-recycling/): 7 EU fact-box stats (3.4M tonnes/yr, 95% recovery rate, composition), 6-route recycling table (rubber crumb/TDF/pyrolysis/devulcanisation/retreading/landfill ban), ambient vs cryogenic grinding comparison, pyrolysis yield breakdown (oil 35–45% / rCB 30–35% / steel 10–15%), ECHA 2021 rubber crumb safety ruling, 4-step legal disposal guide, retreading reuse stats (30–40% less oil than new tyre).
- [Tyre load capacity guide](https://tirefitlab.com/learn/tyre-load-capacity/): 15-row load index table (LI 71–121, kg and lb), 7-row inflation pressure vs capacity table (1.5–3.5 bar), SL vs XL vs Commercial fitment comparison, GVWR calculation worked example (1,800 kg / 4 = 450 kg / LI 80), single vs dual fitment load reduction rule (~88–91%), 6-point overload symptom checklist.
- [Tyre mixing guide](https://tirefitlab.com/learn/tyre-mixing/): 6-row axle rule table (same model/different brand/radial+bias/different size/different speed rating/different load index with legal status and safety concern), 6-row tyre type mixing table (summer+winter/summer+all-season/all-season+winter/run-flat+standard/run-flat+run-flat/full winter set with legal status and why it matters), 6-row country regulation table (DE/FR/ES/UK/USA/EU-ECE-R54 with mixing rules and penalties), 4-row brand mixing scenario table with verdict and recommendation, new-tyres-front-or-rear consensus explanation (rear always regardless of drivetrain), speed rating mismatch rule (lower rating always to rear).
- [TPMS guide](https://tirefitlab.com/learn/tpms/): 8-row direct vs indirect TPMS comparison table (measurement method/which tyre identified/threshold/accuracy/reset/battery/cost/regulation), 4-row warning light state table (solid/flashing/disappears after driving/after rotation with meaning and action), step-by-step indirect TPMS reset procedure (6 steps), 5-row TPMS limitation table (slow leak below 25%/uniform under-inflation/temperature compensation/spare tyre/run-flat tyres), winter wheel sensor options (3 choices: fit sensors/transfer/no sensors), TPMS sensor battery end-of-life symptoms and replacement requirement, 315/433 MHz frequency note.
- [EV tyre guide](https://tirefitlab.com/learn/ev-tyres/): 5-row EV demand table (weight/torque/cabin silence/range/regen braking with explanation and tyre response), acoustic foam 6-row feature table (construction/mechanism/noise reduction/weight/repair compatibility/cost), 5-row rolling resistance vs range impact table (A–E EU label), 4-row EV load index table by vehicle type with per-corner load estimates, standard tyre compatibility guidance (legal but with tradeoffs), 6-row EV tyre brand marking table (ContiSilent/Michelin Acoustic/Goodyear SoundComfort/Pirelli Elect/Bridgestone Enliten), EV tyre wear patterns (FWD/RWD/AWD asymmetry, regen braking cold compound).
- [Tyre tread pattern guide](https://tirefitlab.com/learn/tyre-tread-patterns/): 4-pattern comparison table (symmetric/directional/asymmetric/block with strengths, weaknesses, typical use), V-channel aquaplaning physics explained, 6-factor aquaplaning risk table (water depth/speed/tread depth/pressure/pattern type/tyre width), asymmetric inner/outer zone design and mandatory OUTSIDE mounting, 4-row rotation restrictions by pattern type, 4-row noise level table (symmetric/directional/asymmetric/block with mechanism), pitch variation noise-reduction technique, A/T vs M/T off-road comparison, 4-step guide to identifying your tyre pattern type.
- [EU tyre label guide](https://tirefitlab.com/learn/eu-tyre-label/): 5-row fuel efficiency table (A–E with rolling resistance N/kN values), 5-row wet braking table (stopping distance differentials at 80 km/h), 3-row noise wave symbol table, two 2021 winter icons (3PMSF snowflake + ice grip), how to balance the three dimensions when buying, what the label does not cover (dry braking/handling/wear/cabin noise).
- [Tyre warranty guide](https://tirefitlab.com/learn/tyre-warranty/): 4-row warranty type table (manufacturing defect/tread wear mileage/road hazard/uniformity with coverage, exclusions, and duration), 8-row void condition table (incorrect inflation/fitment/racing/overloading/no rotation/mounting damage/modification/road hazard), pro-rata tread wear warranty explanation with 3 worked examples (40k/70k km, 55k/60k km, 10k/80k km), manufacturer vs retailer vs road hazard cover distinction, DOT date code warranty expiry rule (6-year limit from manufacture not purchase), 6-step warranty claim procedure.
- [Tyre speed rating vs use guide](https://tirefitlab.com/learn/tyre-speed-rating-vs-use/): 13-row speed symbol table (N through Y and (Y)/ZR with km/h, mph, typical application), 4-row consequence table (brief exceedance/sustained 10–20 km/h over/sustained 30+ km/h over/heat+load combined with risk level and action), heat-failure physics (hysteresis, rubber softening, belt delamination, cord fatigue), 4-stage ECE R30 test procedure explanation (indoor drum/post-test inspection/load test/ZR-Y qualification), 4-row legal status table (EU/UK/Germany/USA with rule, penalty, speed sticker requirement), how to find vehicle minimum speed rating (CoC/owner manual/door sticker hierarchy), 4-row speed rating mixing table (same axle/lower rear/seasonal changeover/ZR+W notation).
- [Tread wear indicators guide](https://tirefitlab.com/learn/tread-wear-indicators/): 5-row depth reference table (8mm/4mm/3mm/1.6mm/0mm with condition, wet braking impact at 80 km/h, and recommendation), TWI bar location guide (4-row: sidewall markings, count/positions, bar appearance, winter secondary 4mm indicator), 4-method depth measurement table (gauge/20p penny test/USA quarter test/TWI bars with accuracy, cost, procedure, limitation), 4-region legal limit table (EU/UK/USA/Canada with summer min, winter min, penalty), 6-row wear pattern diagnosis table (centre wear/edge wear/one-sided shoulder/feathering/cupping/flat spot with cause and action), when to check tread depth (monthly visual, pre-winter, long trips, post-alignment, used vehicle purchase).
- [Balancing vs alignment guide](https://tirefitlab.com/learn/balancing-vs-alignment/): 8-row comparison table (what it corrects/primary symptom/secondary symptom/technician procedure/tools/frequency/typical cost/consequences of skipping — balancing vs alignment side by side), 8-row symptom diagnosis table (steering vibration at speed/vehicle drifts/steering off-centre/inner edge wear/centre wear/shoulder wear/cupping/wandering — likely cause and service), 4-row alignment angles table (toe/camber/caster/thrust angle with definition, symptom if wrong, adjustability), list of when both services are needed together (pothole impact/new tyre fit/suspension repair/seasonal changeover), two-wheel vs four-wheel alignment choice guide, static vs dynamic imbalance distinction.
- [Trailer and caravan tyre pressure guide](https://tirefitlab.com/learn/trailer-tyre-pressure/): 6-row pressure table by trailer type (small box trailer 750kg/leisure caravan 1100-1500kg/twin-axle caravan 1500-2000kg/horse box/boat trailer/car transporter — tyre size, bar range, notes), 4-row load-vs-pressure table (empty through GVW — always use full laden pressure), 6-row common mistakes table (using car pressure/checking hot/ignoring pre-trip checks/flat spare/nitrogen myth/ignoring age — mistake, consequence, fix), 4-row tyre age risk table (under 5yr/5-7yr/7-10yr/over 10yr — risk level and action), 4-row valve type table (TR413/TR415/TR416/TPMS — suitability, max pressure, notes), TPMS section, 8-step pre-departure towing checklist.
- [Staggered tyre fitment guide](https://tirefitlab.com/learn/tyre-stagger-fitment/): 7-row staggered examples table (BMW M3/M4/M5/M8/Porsche 911 Carrera S/718 Cayman GT4/Ferrari F8/Corvette C8/Audi RS6 — front size, rear size, stagger mm, reason), why wider rears improve RWD (friction circle dual-task explanation), 6-row staggered vs square implications table (rotation/rear wear rate/spare tyre/side-to-side swap/winter fitment/replacement cost — staggered vs square vs impact), winter tyre square conversion examples (BMW M3 275/35R18 all-round, Porsche 911 245/40R20 all-round), 3-row how-to-check table (sidewall reading/owner's manual/tyre placard).
- [Tyre section width effects guide](https://tirefitlab.com/learn/tyre-section-width-effects/): 6-row width class comparison (155–175 through 275–335 mm — example sizes, dry grip, wet grip, rolling resistance, fuel effect, noise, notes), 8-row width effect direction table (dry cornering/aquaplaning/rolling resistance/fuel/noise/wet braking/snow/steering feel — wider vs narrower vs magnitude vs notes), 6-row rim width ETRTO limits table (5.0–5.5" through 10.0–11.0" — min/max/optimal tyre width mm), aquaplaning physics explanation (contact pressure knife-vs-snow-plow model, 5 variables), 5 use cases for narrower than OEM width (EV range/winter snow/high rainfall/fuel economy/always check rim limits).
- [Summer tyre cold weather guide](https://tirefitlab.com/learn/tyre-cold-weather-summer/): 6-row temperature performance table (20°C through −10°C — compound state, wet braking index, dry braking index, snow grip index, notes), 4-row compound physics table (polymer chain mobility/glass transition temperature/hysteresis/road interlocking — high temp vs low temp vs grip effect), 4-row tyre type comparison (summer/all-season 3PMSF/all-season M+S only/winter — above 7°C, below 7°C, snow, 3PMSF marking, best for), 7°C threshold practical interpretation (night lows vs daytime highs, surface vs air temperature, shaded sections, seasonal vs daily), 5-row legal requirements table (Germany situational StVO/Austria mandatory Nov–Apr/Nordic mandatory/UK no mandate/France–Spain mountain areas), 4-point regional decision guide (southern/central/northern Europe/UK).
- [Tyre aspect ratio and handling guide](https://tirefitlab.com/learn/tyre-aspect-ratio-handling/): 6-row aspect ratio series comparison (<35 through 75–80 — example sizes, sidewall height mm, handling, ride, noise, typical use), 7-row sidewall height effect table (lateral stiffness/steering response/ride comfort/noise/load capacity/rim protection/aquaplaning — lower AR vs higher AR vs why), 2-row plus-sizing example table (stock/+1/+2 — sidewall height change, handling, ride risk, notes), EV fitment note (heavier vehicles favour higher aspect ratios for load and rolling resistance), 5-point practical guidance by use case (daily road/poor surfaces/performance daily/track/EV).
- [Tyre ply rating and load range guide](https://tirefitlab.com/learn/tyre-ply-rating/): 6-row load range table (B through G — ply rating equivalent, max psi/bar, notes), 6-row LT vs P-metric comparison (designation/sidewall/load capacity/pressure/tread depth/off-road — LT vs P-metric vs practical implication), 5-row example load capacity table (LT225/75R16 C through LT265/70R17 E — max pressure, single kg, dual kg), ST special trailer tyre table, passenger car Standard Load vs Extra Load (XL/RF) explanation with 10–15% capacity difference, how to read load range from sidewall (LT265/70R17 121/118R E example decoded), 3 rules for choosing the right load range (never fit lower/higher OK with ride penalty/always match pressure to load condition).
- [Tyre speed rating exceedance guide](https://tirefitlab.com/learn/tyre-speed-rating-exceeded/): 12-row speed symbol table (N through (Y)/ZR — max km/h, max mph, typical application), ECE Regulation 30 test methodology, heat generation physics (increases with speed squared — 20% above rating = 44% more heat per unit time, 30% above = 69% more), 4-row exceedance consequence table (0–5%/5–15%/15–25%/>25% — heat effect, structural risk, legal risk, real example), 5 compounding risk factors (under-inflation/high ambient/near-max load/tyre age/previous damage), 4-row legal position table (Germany §36 StVZO/UK Road Traffic Act 1988/France Code de la Route/EU WVTA — requirement, penalty), 3-row winter speed-label table (Q-rated winter/T-rated all-season/ZR or W or Y summer in over-spec — legal position, practical considerations), how to locate speed rating on sidewall and in vehicle documents.
- [Tyre cornering stiffness and slip angle guide](https://tirefitlab.com/learn/tyre-cornering-stiffness/): 5-row slip angle table (0° through >12–15° — lateral force, phase, description), cornering stiffness coefficient Cα definition and typical values (road 500–1500 N/° vs F1 5000–12000 N/°), 7-row cornering stiffness factor table (width/compound/pressure/load/tread depth/camber/temperature — effect, direction, practical implication), 4-row understeer/oversteer table (neutral/understeer/oversteer/lift-off oversteer — definition, cause, driver experience, safety), friction circle combined-loading physics (lateral vs longitudinal grip trade-off with percentages), tyre matching advice (wider/softer rear = stability, wider/softer front = reduced understeer).
- [Tyre wear patterns guide](https://tirefitlab.com/learn/tyre-wear-patterns/): 7-row wear pattern diagnostic table (centre wear/both-shoulder/one-sided/cupping-scalloping/heel-toe/patchy/feathering — description, primary cause, mechanism, additional causes, fix, urgency), 5-row symptom-based diagnosis table (vibration/thumping/pulls to side/fast wear/new tyres wearing fast — likely cause, what to check), how to manually read tyre wear by touch (height differences, side-to-side, rib edge sharpness, wavy texture, flat spots), why abnormal wear affects safety beyond tyre life (asymmetric braking, contact loss during cupping, aquaplaning risk).
- [Tyre hydroplaning speed guide](https://tirefitlab.com/learn/tyre-hydroplaning-speed/): critical speed formula V ≈ 9.0 × √P km/h (P = inflation pressure in bar), 6-row critical speed table (8 mm through 1.6 mm tread × four pressures 2.1–2.8 bar — approximate onset speeds), 6-row physics factor table (tread depth/pressure/width/pattern/water depth/load — effect, direction, magnitude), 6-row tread depth wet performance index table (wet braking index and aquaplaning speed index referenced to new tyre = 100), 5-step aquaplaning recovery procedure (do not brake/do not steer sharply/ease throttle/hold steering/brake gently after contact resumes), why wider tyres aquaplane earlier (knife-through-water principle), prevention checklist (3 mm replacement, correct pressure, slow in rain, avoid ruts).
- [Tyre heat buildup guide](https://tirefitlab.com/learn/tyre-heat-buildup/): 3-row heat source table (hysteresis ~80–90%/friction ~8–15%/air compression ~2–5% — mechanism, affected-by, location), 3-row DOT temperature grade table (A/B/C — heat resistance, tyre types, notes), hot vs cold pressure rule (never deflate a hot tyre), 4-row pressure rise table (city/motorway 30min/track/summer laden — cold spec, hot reading, rise), 5-row dangerous heat factor table (under-inflation/overloading/high speed/hot ambient/combined — mechanism, heat increase, consequence), 3-row monitoring table (TPMS/manual gauge/IR thermometer), visual heat damage recognition (tread crazing, belt bubble, vibration, flat spots).
- [Tyre contact patch guide](https://tirefitlab.com/learn/tyre-contact-patch/): contact patch size calculation (P=F/A: area ≈ load ÷ pressure), 5-row size table (185/65 R15 through 275/35 R20 — corner load, pressure, approx area/length/width), 4-row pressure effect table (correct/under/over/laden — patch shape, wear pattern, grip effect), 6-row narrow vs wide tyre comparison (dry cornering/wet grip/dry braking/snow/fuel/comfort — narrower vs wider vs verdict), 4-row vehicle dynamics table (emergency braking/max cornering/traction/aquaplaning — patch role, technical detail), friction circle explanation (longitudinal vs lateral force trade-off), tread depth vs wet drainage (3 mm = ~50% wet capacity of new tyre, 1.6 mm = ~25–35%).
- [Tyre overloading guide](https://tirefitlab.com/learn/tyre-overloading/): 10-row load index reference table (LI 71–109: kg per tyre, lbs, typical vehicle class), 4-row overload consequence table (1–5% through >20% overload — heat increase per revolution, tyre life impact, failure risk, typical cause), 4-row load vs pressure scenario table (correct load+pressure/under-inflated/overloaded/overloaded+under-inflated — sidewall flex, heat, behaviour), 5-row common situation table (5 adults+boot/roof box/towing/LCV/wrong LI tyre — risk level, detail, action), 5-step load check procedure, legal position (UK Road Traffic Act, German StVZO §29, EU ECE Reg 54, insurance implications).
- [Directional vs non-directional tyre guide](https://tirefitlab.com/learn/tyre-directional-vs-non-directional/): 4-row tyre orientation type table (directional/non-directional symmetrical/asymmetric/directional+asymmetric — tread pattern, sidewall marking, how to identify, rotation rules, whether can fit either side, examples), 5-row backwards-fit consequences table (wet drainage/aquaplaning/noise/dry performance/wear — severity, technical detail, real-world effect), 4-row rotation pattern table (non-directional/directional/asymmetric/directional+asymmetric — allowed patterns, specific rotations, spare inclusion), 3-row spare tyre scenario table, visual identification procedure (V-apex direction + arrow direction check), mixing directional and non-directional tyres on same axle — safety implications.
- [Wheel bolts vs studs guide](https://tirefitlab.com/learn/wheel-bolts-vs-studs/): 6-row system comparison table (how it works/installation/EU vs US markets/UK vehicles/strength/thread engagement — bolt side vs stud side), 6-row thread size table (M12×1.5/M12×1.25/M14×1.5/M14×2.0/7/16-UNF/1/2-UNF — common vehicles, wrench size, torque Nm), 4-row seat type table (conical 60°/spherical BMW R12-R14/flat/mag — description, brands, dangers of wrong type including BMW ball-seat on aftermarket wheels), 5-row torque guide by vehicle type (small/medium/large/LCV/US-market — thread, Nm, retorque), 6-row common mistakes table (overtorque/undertorque/wrong seat type/lubricating threads/cross-threading/wrong bolt length — consequence + fix), 4-row stud conversion table (why/how/downsides/legality), 4-step torquing procedure (star pattern, snug then final, retorque after 50-100km).
- [Tyre rolling resistance guide](https://tirefitlab.com/learn/tyre-rolling-resistance/): 5-row EU label fuel efficiency grade table (A through E — L/100km savings vs G, CO2 delta, typical Crr range 0.006–0.015, tyre types), 6-row Crr factors table (compound softness Shore A/tyre pressure/temperature/tyre width/tread depth/carcass construction — impact direction + magnitude), 3-row silica vs carbon black compound table (traditional/silica/max-grip — Crr, wet grip, tread life), 4-row EV considerations table (range/load capacity/noise/torque wear), hysteresis physics explanation, rolling resistance % of total fuel consumption at different speeds (80/100/130 km/h), practical reduction tips (pressure/EU grade A-B selection/width choice/alignment).
- [Road hazard tyre warranty guide](https://tirefitlab.com/learn/tyre-road-hazard-warranty/): 4-row covered events table (irreparable nail/screw puncture/pothole carcass damage/sharp debris/tread separation — covered status, condition, notes), 8-row exclusions table (repairable puncture/normal wear/kerb impact/vandalism/incorrect inflation/misalignment/off-road/track use — reason + action), 5-row pro-rata credit table (100%/75%/50%/25%/at minimum tread — credit level, example calculation), 6-step claim procedure (keep tyre/document/go to retailer/present purchase docs/allow inspection/receive credit), 5-row worth-buying guide (high mileage/urban poor roads/expensive tyres/low mileage/budget tyres — verdict), manufacturer defect warranty vs road hazard distinction, European vs North American market context.
- [UTQG tyre ratings guide](https://tirefitlab.com/learn/tyre-utqg-ratings/): 5-row treadwear index table (300+/200-299/100-199/60-99/below 60 — life vs reference, typical tyre types, grip level, notes), 4-row traction grade table (AA/A/B/C — wet stopping distance, test method, in-practice tyre types), 3-row temperature grade table (A/B/C — heat resistance, test speed, common tyre types), 4-row exempt tyre table (winter/T-spare/competition/off-road — reason + alternative), 4-row UTQG limitation table (cross-manufacturer reliability/traction is straight-line only/temperature is not speed rating/treadwear vs grip relationship), sidewall marking format (TREADWEAR 320 TRACTION A TEMPERATURE A), EU Tyre Label vs UTQG comparison, practical buying guide by use case (daily driver/performance/track).
- [Tyre flat spot guide](https://tirefitlab.com/learn/tyre-flat-spot/): 4-row flat spot type table (temporary cold/permanent skid/storage/heat cycling — cause, symptoms, duration, repairable status, risk level), 4-row physics table (viscoelasticity/compound hardness Shore A/contact patch geometry/skid abrasion depth — explanation + implication), 5-row decision guide (vibration disappears vs persistent vs skid vs post-braking vs post-storage — verdict, action, replace tyre?), 6-row prevention table (inflation/jack stands/move vehicle/max pressure storage/ABS/parking-after-drive), tyre-type-specific notes (winter compound, UHP summer, run-flat), how to distinguish permanent from temporary via driving test and visual/tactile tread inspection.
- [Alloy wheel repair guide](https://tirefitlab.com/learn/alloy-wheel-repair/): 8-row damage assessment table (kerb scuff/minor buckle <3mm/moderate buckle 3-8mm/severe buckle or bead seat/cosmetic crack/small hairline crack mid-spoke/crack at spoke root or bead seat/through-crack — structural risk, repairable status, method, cost, notes), 5-row repair methods table (SMART cosmetic/diamond cutting/hydraulic press/TIG welding/full refurbishment — suitability, process, quality, cost), 5-row drive-urgency table (minor scuff/vibration/buckle/bead leak/visible crack — safe to drive?, urgency), alloy metallurgy (cast vs forged grain structure, fatigue crack propagation, stress concentration physics at crack tips), UK MOT and German TÜV/HU implications for repaired wheels.
- [Low-profile tyres guide](https://tirefitlab.com/learn/low-profile-tyres/): 5-row aspect ratio category table (70–75 standard / 55–65 medium / 45–50 low / 35–40 very low / 25–30 ultra-low — typical applications, sidewall height examples, characteristics), sidewall height formula (section width × AR/100) with worked examples (225/45=101mm, 225/35=79mm, 255/25=64mm), 6-row handling comparison (cornering/contact patch/steering feel/ride/noise/wet grip — low profile vs standard, winner, notes), 4-row damage risk table (belt separation/rim damage/kerb damage/winter performance — risk level, mechanism, signs, action), 3-row upsizing scenarios (one-size/two-size/extreme — AR change, diameter matching, ride, damage risk, speedometer), TPMS importance for low-profile (invisible underinflation problem), winter upsizing advice (fit smaller-diameter winter wheel set).
- [Tyre blowout guide](https://tirefitlab.com/learn/tyre-blowout/): 6-row cause table (under-inflation/structural damage/overloading/impact/age/repair failure — likelihood, mechanism, warning signs, prevention), 7-step blowout control procedure (hold steering/maintain throttle 2–3 sec/no hard braking/signal/slow gradually/stop safely/hazard lights — counterintuitive throttle-maintenance explained), front vs rear blowout handling differences, 6-row warning signs table (tread bulge/sidewall bulge/vibration/steering pull/TPMS warning/tyre age — urgency and meaning), 7-item prevention checklist (monthly cold pressure check/bulge inspection/DOT age/load index/road hazards/post-impact inspection/run-flat use).
- [Tyre bead damage guide](https://tirefitlab.com/learn/tyre-bead-damage/): bead anatomy (wire bundle/filler/toe/heel/chafer), hoop stress physics (800–1,200 N per cm at 2.5 bar), 6-row cause table (kerb mounting/fitting machine/running flat/corroded rim/bead unseating/over-inflation — description, detection, prevention, repairable status), 5-row identification table (bead leak/non-uniform seating/kink visible/rim contact marks/torn bead toe — soapy water test, cause, action), 7-step bead seating procedure (50 psi OSHA limit, re-lubricate before exceeding 40 psi), 4-row rim bead seat condition table (light corrosion/heavy pitting/bent flange/cracked flange), safe driving guidance when bead fails at speed.
- [Tyre delamination guide](https://tirefitlab.com/learn/tyre-delamination/): 5-row delamination type table (tread separation/belt separation/sidewall delamination/inner liner delamination/tread chunk — description, visual signs, causes, danger level, action), 6-row root cause table (chronic under-inflation/impact damage/UV-ozone age/improper repair/overloading/manufacturing defect — mechanism, risk, prevention), explanation of why a tread bulge is always belt failure and not repairable, 4-row inspection guide (tread face/shoulders/sidewall/inner liner — method, warning signs, action), delamination vs normal wear identification guide (6 scenarios), EU/UK legal position on repairing delaminated tyres (ETRTO, BS AU 159).
- [Wheel spacers guide](https://tirefitlab.com/learn/wheel-spacers/): 4-row spacer type comparison (hub-centric slip-on/lug-centric/bolt-on thread-through/stud conversion PCD adapter — centring method, mounting, suitability, Germany legal status, notes), 4-row spacer thickness vs ET impact table (5mm/10mm/20mm/30mm — ET change, track widening, clearance concerns, steering effect), 5-row country legality table (Germany TÜV/ABE/Einzelabnahme requirement, UK MOT basis, EU general, Austria, Switzerland), 6-row safety risk table (thread engagement/lug-centric centering/wrong thread pitch/galvanic corrosion/incorrect torque/tyre protrusion — cause, consequence, prevention), 7075 vs 6061 aluminium alloy explanation, 7-step installation procedure with re-torque schedule.
- [Tyre valve types guide](https://tirefitlab.com/learn/tyre-valve-types/): 6-row valve type comparison table (TR413 rubber snap-in/TR414-415 extended/metal clamp-in TR416-TR418/TPMS sensor valve/indirect TPMS/high-pressure TR600HP — appearance, application, max pressure, replacement interval, cost, notes), why rubber valves must be replaced at every tyre change (ozone/heat/UV degradation, €0.50 vs €25 demount cost), 5-row valve core maintenance table (slow leak/core replacement/missing cap/bent stem/corrosion — cause, soapy water test, action), 5-row TPMS service table (seasonal swap/new tyres on existing wheels/warning light after change/dead battery/winter steel wheels without sensors — action and cost), valve cap selection guide (plastic/O-ring metal/locking/TPMS-specific), valve hole sizing (11.3 mm passenger vs 15.7 mm commercial, grommet matching for metal clamp-in upgrade).
- [Are used tyres safe — buyer's guide](https://tirefitlab.com/learn/used-tyres/): 9-point inspection checklist (tread depth/sidewall bulges/sidewall cuts/plug repairs/DOT age/ozone cracking grade/wear pattern/run-flat history/re-grooving — method, pass threshold, reject if criteria), 4-row hidden risk table (internal cord damage/hidden plug/chemical contamination/incorrect storage — cause, external visibility, consequence, mitigation), 5-row acceptability table (budget winter spare set/temporary spare/daily driver/high-speed use/classic vehicle — assessment, conditions, note), UK/EU legal position (no prohibition on used tyres, liability risk for garage fitting known defects), DOT date code decoder (WWYY format, pre-2000 3-digit code = reject, age from manufacture not purchase), price comparison (used €20-50 vs budget new €45-80 per tyre, risk-saving analysis).
- [Tyre size conversion guide](https://tirefitlab.com/learn/tyre-size-conversion/): 6-row format reference table (metric/P-metric/LT-metric/flotation/classic inch/alpha-numeric — example, market, structure, decoded, notes), 5 conversion formulas with worked examples (metric OD formula/flotation→metric/metric→flotation/classic inch→metric/P-metric→Euro-metric load capacity with the 10% TIA/RMA reduction), P-metric vs Euro-metric differences explained (physically identical tyres, 10% load capacity reduction for TIA single-fitment, practical irrelevance for most passenger cars), 8-row metric↔flotation equivalents table (145R13 through 35×12.50R17LT with OD and notes), 8-row classic inch↔modern metric table (5.20-13 through 7.10-15 with vehicle examples), LT Load Range explained (C/D/E/F with ply rating equivalent and max psi).
- [Winter tyre laws by country](https://tirefitlab.com/learn/winter-tyre-laws/): 15-row country-by-country legal requirements table (Germany/Austria/Switzerland/Czech Republic/Finland/Sweden/Norway/France/Spain/Italy/Poland/Netherlands/UK/Belgium/Russia — law type, dates or conditions, minimum tread depth, required marking, typical fine, notes), 4-row qualifying tyre marking table (3PMSF/M+S/studded/M+S edge case — appearance, legal acceptance, performance basis), Germany situational mandate explained (§2 Abs. 3a StVO — snow/ice/frost conditions, €60 tyre fine + €120 obstruction fine), 7°C threshold physics (summer compound hardening, 10–20% braking distance increase on cold dry road), 6-row tread depth recommendation table (8mm new through 1.6mm minimum — condition and recommendation), studded tyre permitted/prohibited country list, cross-border driving guidance (fitting strictest applicable standard before departure).
- [Tyre pressure for heavy loads and towing](https://tirefitlab.com/learn/tyre-pressure-load/): unladen vs full-load pressure explained (door sticker two-column guide), 5-row load scenario table (solo/full load/towing/motorway/boot cargo — front and rear bar with notes), XL vs SL tyre pressure distinction (6-row table LI 91–107 with SL and XL bar and rated kg), 5-row SL vs XL comparison table (load at 2.5 bar/OEM requirement/door sticker reading/ride quality/sidewall identification — risk of mismatch), towing nose weight physics (75 kg nose weight → rear axle overload, tongue weight pitch transfer), 4-row under-inflation consequences table (sidewall overloading/heat build-up/contact patch distortion/handling degradation — mechanism, consequence, timeline), motorway pressure rise explained (0.2–0.4 bar hot, do not deflate after driving), TPMS 25% threshold limitation (2.8 bar laden → warns only at 2.1 bar, manual pre-journey check essential), 6-step pre-loaded-journey checklist (identify XL/SL/find door sticker/check cold/set laden/set front vs rear/recheck at 50 km).
- [Rim width and tyre fitment guide](https://tirefitlab.com/learn/rim-width-tyre-fitment/): 21-row ETRTO rim width compatibility table (section width 155–355 mm with minimum/ideal/maximum rim width in inches), 6-row too-narrow rim effects table (section width increase/effective aspect ratio increase/bead security risk/rolling resistance/oversteer tendency/rim damage — severity rating), 6-row too-wide rim effects table (section width decrease/effective aspect ratio decrease/sidewall damage/ride harshness/understeer tendency/bead deformation — severity rating), 4-row rim width change impact table (+0.5"/+1.0"/+1.5"/−0.5" with section width change mm, effective aspect change, practical effect), 6-row rim marking decoder (width J-width/diameter/ET offset/centre bore/bolt circle PCD/load rating with example, how to read, and notes), 6-step practical fitment guide (tyre section → ETRTO range → current rim check → overall diameter → ET and arch clearance → centre bore → load rating), plus-sizing rim width compatibility section.
- [Crossply vs radial tyre construction](https://tirefitlab.com/learn/crossply-vs-radial/): 10-row construction comparison table (cord angle/sidewall-tread relationship/belt plies/sidewall stiffness/heat generation/rolling resistance/ride comfort/tread wear/cornering/sidewall marking — crossply vs radial and why it matters), 4-row size format table (imperial crossply 6.00-16/metric radial 195/65R15/belted bias/alpha-numeric with era), why radial won passenger cars (tread life 30-50% longer/fuel 3-6% saving/high-speed standing wave prevention/wet grip), 8-row current applications table (passenger cars radial/vintage pre-1960 crossply/1960s-70s either/agricultural both/OTR both/karting crossply/small motorcycles/aircraft crossply — reason), 4-row mixing prohibition table (crossply front+radial rear/radial front+crossply rear/crossply spare on radial car/two of each — legal and safety risk), 3-method identification table (size designation R/word on sidewall/physical flex test), classic car guidance (FIVA rules/pre-1960 suspension geometry/narrow rim compatibility/1960s-70s exceptions).
- [Spare tyre types](https://tirefitlab.com/learn/spare-tyre-types/): 5-row type comparison table (full-size matching/space-saver temporary/run-flat/mobility kit/full-size non-matching — speed limit, distance limit, weight, cost, best-for), 5-row space-saver rules table (speed limit 80 km/h/distance limit/axle placement/AWD prohibition/TPMS warning — detail and consequence of ignoring), run-flat "80/80 rule" explanation (reinforced sidewalls, heat limitation, must replace after any run-flat use, no mixing with standard), 5-row mobility kit scenarios table (works for tread puncture ≤4mm/does not work sidewall/does not work RFT blowout/unusable after sealant/TPMS sensor compatibility), 5-row OEM policy table (BMW/Tesla/VW Group/Toyota/Stellantis — spare policy, kit, full-size available), trend away from spare tyres (35% of new EU cars without full-size spare by 2023, EV battery space constraint), 5-row spare maintenance table (tread depth/cold pressure monthly/sidewall cracking/DOT age/mobility kit expiry — frequency and what to check), legal requirements section (no EU/UK law requires spare in private car).
- [MOT and roadworthiness tyre requirements](https://tirefitlab.com/learn/mot-tyre-requirements/): 7-row inspection table (tread depth/sidewall condition/inflation and TPMS/axle type consistency/speed and load rating/re-grooving/spare — standard, fail criteria, notes), tread depth mechanics (central ¾ width rule, circumference, TWI bar flush = legal limit, 3mm wet safety recommendation vs 1.6mm legal floor), 7-row country comparison table (UK MOT/Germany HU/France CT/Spain ITV/Italy revisione/Poland/Netherlands APK — frequency, tread min, mixing rule, speed rating, TPMS, authority), tyre mixing rules (crossply vs radial prohibited on same axle; brands/patterns/compounds legal to mix), TPMS and roadworthiness (UK 2023: TPMS light = major defect/fail; EU 2014/45/EU), 5-row common failure reasons table (tread below 1.6mm/bulge or cord exposure/TPMS light/speed rating below spec/re-grooved without RG — frequency and prevention), 6-row pre-test checklist (tread/sidewall/inflation/TPMS/speed rating/construction type check with tool and threshold), puncture repair legality (internal mushroom patch tread = legal; sidewall = no; plug only = not permanent; RFT run-in = replace).
- [EV and hybrid tyre speed ratings](https://tirefitlab.com/learn/ev-tyre-speed-rating/): 4-row why-EVs-need-higher-ratings table (instant torque/sustained power/battery weight/regenerative braking — technical detail and tyre implication), 5-row EV speed rating table (H/V/W/Y/(Y) with max speed, common EV applications, notes — Tesla Model 3/BMW i4/Porsche Taycan examples), 5-row EV tyre marking table (EV designation/XL Extra Load/acoustic foam/self-sealing/run-flat — meaning, examples, mandatory to match), load index section (why EVs need higher load index, XL vs standard load pressure difference, 100 kg per corner example), 4-row PHEV/HEV/MHEV/BEV comparison table (speed rating/load index/torque impact), tread wear 20–30% faster explanation (instant torque/weight/regen braking with tyre-specific compound solutions), acoustic foam cavity resonance section (200–250 Hz, 6–9 dB reduction, cannot be retrofitted), 6-step EV tyre replacement checklist (OEM speed rating/load index/XL/acoustic foam/RFT mixing/TPMS calibration).
- [Tyre inspection checklist](https://tirefitlab.com/learn/tyre-inspection-checklist/): 10-row monthly inspection checklist (tread depth/inflation pressure/sidewall bulge/sidewall cracks/embedded objects/uneven wear/DOT age/valve/TPMS light/overall visual — how to check, pass criteria, fail action, frequency), 5-row coin tread depth test table (UK 20p/UK 1p/US quarter/US penny/EU 2 cent — outer band depth and interpretation), 6-row wear pattern diagnosis table (centre wear/both edge wear/one-sided shoulder/feathering/cupping/flat spot — cause and action), 8-row professional urgency table (bulge/cord visible/below 1.6mm/embedded nail/3mm wet market/Grade 2+ cracks/persistent uneven wear/TPMS sensor fault — urgency and action), printable 5-item 5-minute summary (pressure/tread/sidewall/objects/valve caps).
- [Tyre retreading guide](https://tirefitlab.com/learn/tyre-retreading/): 9-row retread vs new tyre comparison (casing/tread compound/tread depth/sidewall/wet grip/dry grip/rolling resistance/raw material use/cost with retread and new columns and verdict), 7-step retreading process table (inspection/buffing/shearography+x-ray/spot repair/tread application/vulcanisation/final QC — with rejection criteria per step), 6-row who-uses-retreads table (trucking/aviation/bus/OTR/passenger cars/military with usage rate and reason), 4-row legal status table (EU/UK/US/Germany with standard, legal status, restrictions, notes), environmental impact section (30-40% raw material saving, 22 vs 7-9 litres oil per tyre, 50-65% lower CO₂ vs new), retread identification guide (RETREAD marking, retreader code, original DOT date vs retread date).
- [Tyre fitting and mounting cost guide](https://tirefitlab.com/learn/tyre-fitting-costs/): 7-row included-services table (demounting/mounting/balancing/valve/disposal/inflation/torque — typically included vs extra, notes), 6-row extra services table (TPMS sensor service/nitrogen/alignment/run-flat service/hub-centric rings/locking nut removal — when needed, typical cost, notes), 5-row price range table by tyre category (compact to commercial van with fitting fee, balancing, and total per-tyre and 4-tyre costs), tyre fitting vs wheel swap distinction (mounting vs seasonal wheel changeover — cost and time difference), 5-row common pitfalls table ("free fitting" online, fitting only without balancing, unnecessary extras, alignment upselling, TPMS sensor replacement upselling), what to bring checklist (TPMS key/tyre size/pressure spec/sensor frequency), 4-step after-fitting check (pressure/bolt retorque at 50 km/TPMS warning light/vibration).
- [Rim types and materials guide](https://tirefitlab.com/learn/rim-types/): 5-row material comparison table (pressed steel/cast alloy/flow-formed/forged alloy/carbon fibre — weight at 18", construction method, impact strength, brake heat dissipation, corrosion resistance, repairability, cost, best-for application), unsprung mass physics (1 kg unsprung ≈ 5–10 kg sprung in handling terms), 5-row manufacturing process table (gravity die casting/LPDC/counter-pressure casting/flow-forming/open-die forging with grain structure and application), brake heat and wheel material section (alloy aluminium at 200°C softening, carbon fibre thermal insulation warning, open-spoke brake airflow design), tyre compatibility checklist (rim diameter/width/offset/centre bore), 6-row repair decision table (kerb scuff/bent barrel steel/bent barrel alloy/bent barrel forged/spoke crack/bead seat corrosion — repairable, method, caveat), steel wheels for winter case (galvanic corrosion, cost, sizing, pothole resistance).
- [Tyre cracking and ageing guide](https://tirefitlab.com/learn/tyre-cracking-ageing/): 6-row crack type table (ozone crazing/UV oxidation/thermal cycling/bead area dry rot/sidewall flexion fatigue/chemical contamination — location, appearance, cause, depth, risk level), 4-grade severity assessment table (Grade 1 cosmetic through Grade 4 critical with visible depth, appearance, action, replace decision), DOT date code age decoder, 5-row age replacement guideline table (ETRTO/UK DVSA/NHTSA/Bridgestone-Michelin-Goodyear/BMW-Mercedes-VW — recommendation, source, legal status), ozone crazing chemistry (antiozonant migration mechanism and why stationary tyres degrade faster), 6-row ageing slowdown measures table (garage UV shelter/correct storage inflation/no petroleum dressings/avoid ozone generators/opaque bags/keep tyres moving), 4 common misconceptions debunked (full tread = safe, all surface cracks serious, tyre dressing prevents cracking, holds air = safe).
- [Tyre wear rate guide](https://tirefitlab.com/learn/tyre-wear-rate/): 7-row wear-rate-by-category table (economy/standard touring/UHP summer/track/winter friction/all-season/C-class van with compound, mm per 10,000 km, practical life km, UTQG range), 8-row wear factor table (speed/inflation/alignment/driving style/road surface/vehicle weight/ambient temperature/rotation with effect, estimated magnitude, and action), UTQG treadwear rating explained (5-row table: ratings 100–600+ with relative durability, typical km, category), 5-row replacement threshold table (7–8 mm new through 0 mm bald with wet braking impact at 80 km/h), 6-step guide to maximising tyre life (cold pressure/alignment/rotation/smooth driving/kerb avoidance/seasonal storage).
- [Tyre upsizing and downsizing guide](https://tirefitlab.com/learn/tyre-upsizing-downsizing/): 4-row plus sizing progression table (plus 0/1/2/3 with example sizes from 205/55 R16 baseline — rim change, section width, sidewall height, OD change %, notes), 9-row performance effects table (dry grip/wet grip/ride comfort/steering response/fuel consumption/noise/impact damage/speedometer/load index — upsizing vs downsizing with caveat), 4-row downsizing use cases (winter tyres/rough roads/fuel economy/track use), speedometer error formula and legal thresholds, 5-row safety rules table (OD within ±3%/load index/speed rating/rim width compatibility/wheel arch clearance), ABS/ESC calibration dependency on tyre OD, AWD rolling circumference mismatch warning.
- [Tyre pressure and fuel economy guide](https://tirefitlab.com/learn/tyre-pressure-fuel-economy/): 5-row under-inflation impact table (0.1 bar / 0.2 bar / 0.4 bar / 0.6 bar / 1.0 bar deficit with rolling resistance increase, fuel increase %, annual fuel cost EUR, annual CO₂ kg, notes), physics of hysteresis and rolling resistance coefficient (RRC), EU label fuel efficiency grades (4-row A/B/C/E with N/kN value, fuel saving vs E, annual saving), 5-row pressure vs efficiency table (OEM spec / +0.1–0.2 bar / +0.3–0.5 bar / max sidewall / −0.4 bar with fuel effect and verdict), 3-row annual saving calculator (monthly check / A- vs E-rated tyre / both combined — with fuel % saved, EUR, and CO₂), EV rolling resistance impact (0.5–0.7 km per 100 km per 0.1 bar under), 5-step correct pressure maintenance checklist.
- [Tyre sidewall markings decoder](https://tirefitlab.com/learn/tyre-sidewall-markings/): 6-row primary size string table (section width/aspect ratio/construction/rim diameter/load index/speed rating with field, example, unit, meaning), 15-row load index quick reference table (LI 75–105 with kg and lbs), 10-row speed rating table (N through Y and ZR with km/h, mph, typical application), 12-row additional sidewall markings table (DOT/M+S/3PMSF/XL/max load/max pressure/UTQG/OUTSIDE/direction arrow/run-flat/made in/E-mark with location, meaning, action), OEM fitment marking guide (BMW star/MO/AO/VOL/RO1), DOT manufacturing date decoder (week + year formula with example), critical max-pressure vs recommended-pressure distinction (sidewall 3.5–4.5 bar vs door-sticker 2.0–2.8 bar).
- [Cold tyre pressure guide](https://tirefitlab.com/learn/cold-tyre-pressure/): 4-row temperature-pressure effect table (+10°C/−10°C/−20°C/+20°C after motorway with pressure change, example, and action), 5-row common pressure-checking mistakes table (warm tyre / heated garage / topping up warm tyre / seasonal neglect / forecourt gauge only — with effect and correct approach), three authoritative pressure sources in priority order (door sticker/owner manual/sidewall max), 4-row seasonal adjustment table (spring/summer/autumn/winter with recommended adjustment and notes), TPMS winter morning warning-light explanation (25% threshold, inflation to spec, re-learn after a few km), 3-row altitude effect table with gauge-pressure vs absolute-pressure distinction, 4-row pressure gauge comparison table (stick/dial/digital/forecourt compressor with accuracy ±%, cost, pros, cons).

## Notes
- Geometry is computed in canonical millimetres; results are deterministic and identical across the site.
- Always verify physical clearance before fitting.