TireFitLab

235/70 R17 vs 33x12.50 R18

235/70 R17 vs 33x12.50 R18

33x12.50 R18 is outside the configured tolerance for 235/70 R17: +10.2% diameter and +10.2% speedometer effect.

Fitment verdict

33x12.50 R18 is outside the configured tolerance for 235/70 R17: +10.2% diameter and +10.2% speedometer effect.

Metric This size: 235/70 R17 Alternative: 33x12.50 R18 Difference Verdict
Overall diameter 29.95 in 33.00 in +10.2% Too tall
Section width 9.25 in 12.50 in +3.25 in Computed difference
Sidewall height 6.48 in 7.50 in +1.02 in Computed difference
Circumference 94.10 in 103.67 in +10.2% Too tall
Speedo 0.0% +10.2% +10.2% Outside tolerance

Compare sizes

Looks valid
Looks valid
Units
✕ Out of toleranceDiameter +10.2% (+3.05 in) · US (~3%)
  • Out of tolerance · Diameter +10.2%.
  • Speedo @ 60: 60 mph → 66.1 mph.
  • Sidewall +1.02 in · Width +3.25 in.
Diameter+10.2%+3.05 in
Speedo @ 60+10.2%60 mph → 66.1 mph
Sidewall+1.02 inWidth +3.25 in
How this result is calculated

Computed from nominal tire-size geometry: diameter, circumference and speedometer error. It does not check wheel-arch, suspension or brake clearance.

Methodology
Diameter
29.95 in 33.00 in+3.05 in
Sidewall
6.48 in 7.50 in+1.02 in
Width
9.25 in 12.50 in+3.25 in
Circumference
94.10 in 103.67 in+10.2%
Revs / mile
673 611
Speedo @ 60
60 mph 66.1 mph+10.2%
Δ⌀ +77.4 mm
  • Current — 235/70 R17
  • New — 33x12.50 R18
  • Grounded to the road: the axle rises +1.52 in.

Result report

235/70 R17 33x12.50 R18 · Out of tolerance

Use this size when shopping: 33x12.50 R18

Use this size when shopping

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

Safe alternative sizes

SizeDiameterSpeedo @ 100Use this
−1″ 295/60R16-0.1%-0.1%
OE 235/70R17+0.0%+0.0%
+1″ 275/55R18-0.1%-0.1%
+2″ 185/75R19-0.1%-0.1%

235/70 R17 · 33x12.50 R18 · Methodology

Last reviewed: 2026-06-28
What changed
  • Reviewed deterministic geometry, load/speed references, sitemap inclusion and localized page shell.