TireFitLab

235/60 R18

What size is 235/60 R18?

235/60 R18 has an overall diameter of about 29.10 in, a section width of 9.25 in and a sidewall height of 5.55 in. It turns roughly 693 times per mile. Below are the exact figures plus plus/minus sizes that stay within the selected diameter tolerance.

Geometric comparison

285/45 R19 stays within the configured tolerance for 235/60 R18: 0.0% diameter and 0.0% speedometer effect.

Geometric comparison
Metric This size: 235/60 R18 Alternative: 285/45 R19 Difference Verdict
Overall diameter 29.10 in 29.10 in 0.0% Within tolerance
Section width 9.25 in 11.22 in +1.97 in Computed difference
Sidewall height 5.55 in 5.05 in -0.50 in Computed difference
Circumference 91.43 in 91.42 in 0.0% Within tolerance
Speedo 0.0% 0.0% 0.0% Within tolerance

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What this geometry means

235/60 R18 has a mid-range sidewall proportion. The marking combines nominal section width 9.25 in, sidewall ratio 60% and rim diameter 18 inches. One sidewall is 5.55 in; both sidewalls make up 38% of the 29.10 in overall diameter, while the rim makes up 62%.

At the nominal 91.43 in circumference, 1,000 rotations cover 2.32 km (1.44 mi); the inverse rates are 431/km and 693/mi.

Section-width mix versus 235/60 R18: 0 narrower, 2 equal-width and 10 wider entries.

The closest diameter entry is 285/45 R19 at -0.0%. Relative to 235/60 R18, it changes nominal section width by +1.97 in, each sidewall by -0.50 in and radius by -0.00 in.

Curated alternatives: 12 sizes, spanning -1.2% to +1.4% in nominal diameter versus 235/60 R18.

Width endpoints in that set are 235/55 R19 (+0.00 in) and 295/40 R20 (+2.36 in) relative to 235/60 R18.

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 29.10 in
Section width 9.25 in
Sidewall height 5.55 in
Circumference 91.43 in
Revolutions 431 /km · 693 /mi

In-tolerance sizes

Alternative sizes that stay within the selected diameter tolerance:

In-tolerance sizes
Size Diameter Speedo Verdict
285/45 R19 -0.0% -0.0% ✓ OK
295/35 R21 +0.1% +0.1% ✓ OK
255/55 R18 -0.2% -0.2% ✓ OK
255/50 R19 -0.2% -0.2% ✓ OK
255/45 R20 -0.2% -0.2% ✓ OK
235/55 R19 +0.3% +0.3% ✓ OK
235/65 R17 -0.3% -0.3% ✓ OK
295/40 R20 +0.6% +0.6% ✓ OK
265/45 R20 +1.0% +1.0% ✓ OK
265/50 R19 +1.1% +1.1% ✓ OK
275/45 R19 -1.2% -1.2% ✓ OK
245/70 R16 +1.4% +1.4% ✓ OK

Compare sizes

Looks valid
Looks valid
Units
High fitment riskWithin tolerance · Diameter -0.0% (-0.00 in) · US (~3%)
  • High fitment risk · This rating covers tire geometry only, not vehicle compatibility.
  • Diameter -0.0% · Ride-height change -0.00 in.
  • Speedometer unchanged · 60 mph → 60.0 mph.
  • Sidewall -0.50 in · Width +1.97 in.
Diameter-0.0%-0.00 in
Speedo @ 60-0.0%60 mph → 60.0 mph
Sidewall-0.50 inWidth +1.97 in
Ride-height change-0.00 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
29.10 in 29.10 in-0.00 in
Sidewall
5.55 in 5.05 in-0.50 in
Width
9.25 in 11.22 in+1.97 in
Circumference
91.43 in 91.42 in-0.0%
Revs / mile
693 693
Speedo @ 60
60 mph 60.0 mph-0.0%
Ride-height change
0.00 in -0.00 in
True distance per 100 indicated
100 mi 100.0 mi-0.0%
Δ⌀ -0.00 inΔ↔ +1.97 in
  • Current — 235/60 R18
  • New — 285/45 R19
  • Grounded to the road: the axle rises -0.00 in.

Result report

235/60 R18 285/45 R19 · High fitment risk · Within tolerance

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

In-tolerance alternative sizes

In-tolerance alternative sizes
SizeDiameterSpeedo @ 100Use this
−1″ 205/75R17+0.0%+0.0%
OE 235/60R18+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