TireFitLab

245/65 R18

What size is 245/65 R18?

245/65 R18 has an overall diameter of about 30.54 in, a section width of 9.65 in and a sidewall height of 6.27 in. It turns roughly 660 times per mile. Below are the exact figures plus plus/minus sizes that stay within the selected diameter tolerance.

Geometric comparison

265/60 R18 stays within the configured tolerance for 245/65 R18: -0.1% diameter and -0.1% speedometer effect.

Geometric comparison
Metric This size: 245/65 R18 Alternative: 265/60 R18 Difference Verdict
Overall diameter 30.54 in 30.52 in -0.1% Within tolerance
Section width 9.65 in 10.43 in +0.79 in Computed difference
Sidewall height 6.27 in 6.26 in -0.01 in Computed difference
Circumference 95.94 in 95.88 in -0.1% Within tolerance
Speedo 0.0% -0.1% -0.1% Within tolerance

Seasonal check

Planning a long summer drive?

Use the budget and running-cost tools before a trip, especially if the current tires are worn or the replacement size changes diameter.

Estimate tire budget

What this geometry means

245/65 R18 has a taller-sidewall proportion. The marking combines nominal section width 9.65 in, sidewall ratio 65% and rim diameter 18 inches. One sidewall is 6.27 in; both sidewalls make up 41% of the 30.54 in overall diameter, while the rim makes up 59%.

Curated alternatives: 12 sizes, spanning -0.6% to +1.5% in nominal diameter versus 245/65 R18.

Width endpoints in that set are 245/70 R17 (+0.00 in) and 285/40 R22 (+1.57 in) relative to 245/65 R18.

At the nominal 95.94 in circumference, 1,000 rotations cover 2.44 km (1.51 mi); the inverse rates are 410/km and 660/mi.

The closest diameter entry is 265/60 R18 at -0.1%. Relative to 245/65 R18, it changes nominal section width by +0.79 in, each sidewall by -0.01 in and radius by -0.01 in.

Section-width mix versus 245/65 R18: 0 narrower, 1 equal-width and 11 wider entries.

This is a nominal geometry comparison only. Vehicle clearance, wheel width and offset, load and speed ratings, and manufacturer approval still require separate checks.

Specification

Specification
Overall diameter 30.54 in
Section width 9.65 in
Sidewall height 6.27 in
Circumference 95.94 in
Revolutions 410 /km · 660 /mi

In-tolerance sizes

Alternative sizes that stay within the selected diameter tolerance:

In-tolerance sizes
Size Diameter Speedo Verdict
265/60 R18 -0.1% -0.1% ✓ OK
265/65 R17 +0.1% +0.1% ✓ OK
245/70 R17 -0.1% -0.1% ✓ OK
265/70 R16 +0.2% +0.2% ✓ OK
265/50 R20 -0.3% -0.3% ✓ OK
265/45 R21 -0.5% -0.5% ✓ OK
265/40 R22 -0.6% -0.6% ✓ OK
275/45 R21 +0.7% +0.7% ✓ OK
275/55 R19 +1.2% +1.2% ✓ OK
285/40 R22 +1.4% +1.4% ✓ OK
31x10.50 R15 +1.5% +1.5% ✓ OK
31x10.50 R16 +1.5% +1.5% ✓ OK

Compare sizes

Looks valid
Looks valid
Units
Minor variationWithin tolerance · Diameter -0.1% (-0.02 in) · US (~3%)
  • Minor variation · This rating covers tire geometry only, not vehicle compatibility.
  • Diameter -0.1% · Ride-height change -0.01 in.
  • Speedometer reads high · 60 mph → 60.0 mph.
  • Sidewall -0.01 in · Width +0.79 in.
Diameter-0.1%-0.02 in
Speedo @ 60-0.1%60 mph → 60.0 mph
Sidewall-0.01 inWidth +0.79 in
Ride-height change-0.01 inDiameter ÷ 2
How this result is calculated

Computed from nominal tire-size geometry: diameter, circumference and speedometer error. It does not check vehicle placard approval, load/speed rating, rim-width range, wheel-arch, suspension or brake clearance.

Methodology

Before fitting

  • Check the vehicle placard and owner’s manual first.
  • Match or exceed the required load index and speed rating.
  • Confirm rim-width range, bolt pattern, hub bore, offset and fasteners.
  • Inspect wheel-arch, suspension and brake clearance under real vehicle load.
  • Check TPMS, cold pressure and local roadworthiness rules.
Diameter
30.54 in 30.52 in-0.02 in
Sidewall
6.27 in 6.26 in-0.01 in
Width
9.65 in 10.43 in+0.79 in
Circumference
95.94 in 95.88 in-0.1%
Revs / mile
660 661
Speedo @ 60
60 mph 60.0 mph-0.1%
Ride-height change
0.00 in -0.01 in
True distance per 100 indicated
100 mi 99.9 mi-0.1%
Δ⌀ -0.02 inΔ↔ +0.79 in
  • Current — 245/65 R18
  • New — 265/60 R18
  • Grounded to the road: the axle rises -0.01 in.

Result report

245/65 R18 265/60 R18 · Minor variation · Within tolerance

Plan budget for this size: 265/60 R18

Copy/print uses this page state only; TireFitLab does not create an account or store a server-side report.

Plan budget for this size
Embed or cite this result
Open embed preview
Budget$100–$140Per tireMid-range$130–$185Per tirePremium$185–$260Per tire

Geometric estimate. Always verify physical clearance (arches, suspension, brakes) before fitting.

In-tolerance alternative sizes

In-tolerance alternative sizes
SizeDiameterSpeedo @ 100Use this
−1″ 215/80R17+0.0%+0.0%
OE 245/65R18+0.0%+0.0%

More tools

Last reviewed: 2026-07-22

Technical check
2026-07-22
Content updated
2026-07-22
What changed
  • Added a localized engine-derived geometry signature and matching Markdown narrative.
Methodology