TireFitLab

31x10.50 R15 vs 33x12.50 R15

31x10.50 R15 vs 33x12.50 R15

33x12.50 R15 is outside the configured tolerance for 31x10.50 R15: +6.5% diameter and +6.5% speedometer effect.

Fitment verdict

33x12.50 R15 is outside the configured tolerance for 31x10.50 R15: +6.5% diameter and +6.5% speedometer effect.

Metric This size: 31x10.50 R15 Alternative: 33x12.50 R15 Difference Verdict
Overall diameter 31.00 in 33.00 in +6.5% Too tall
Section width 10.50 in 12.50 in +2.00 in Computed difference
Sidewall height 8.00 in 9.00 in +1.00 in Computed difference
Circumference 97.39 in 103.67 in +6.5% Too tall
Speedo 0.0% +6.5% +6.5% Outside tolerance

Compare sizes

Looks valid
Looks valid
Units
✕ Out of toleranceDiameter +6.5% (+2.00 in) · US (~3%)
  • Out of tolerance · Diameter +6.5%.
  • Speedo @ 60: 60 mph → 63.9 mph.
  • Sidewall +1.00 in · Width +2.00 in.
Diameter+6.5%+2.00 in
Speedo @ 60+6.5%60 mph → 63.9 mph
Sidewall+1.00 inWidth +2.00 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
31.00 in 33.00 in+2.00 in
Sidewall
8.00 in 9.00 in+1.00 in
Width
10.50 in 12.50 in+2.00 in
Circumference
97.39 in 103.67 in+6.5%
Revs / mile
651 611
Speedo @ 60
60 mph 63.9 mph+6.5%
Δ⌀ +50.8 mm
  • Current — 31x10.50 R15
  • New — 33x12.50 R15
  • Grounded to the road: the axle rises +1.00 in.

Result report

31x10.50 R15 33x12.50 R15 · Out of tolerance

Use this size when shopping: 33x12.50 R15

Use this size when shopping

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

Safe alternative sizes

SizeDiameterSpeedo @ 100Use this
−1″ 335/65R14+0.5%+0.5%
OE 255/80R15+0.2%+0.2%
+1″ 345/55R16-0.2%-0.2%
+2″ 355/50R17-0.1%-0.1%

31x10.50 R15 · 33x12.50 R15 · Methodology

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