TireFitLab

305/40 R22 vs 35x12.50 R18

305/40 R22 vs 35x12.50 R18

35x12.50 R18 is outside the configured tolerance for 305/40 R22: +10.7% diameter and +10.7% speedometer effect.

Fitment verdict

35x12.50 R18 is outside the configured tolerance for 305/40 R22: +10.7% diameter and +10.7% speedometer effect.

Metric This size: 305/40 R22 Alternative: 35x12.50 R18 Difference Verdict
Overall diameter 31.61 in 35.00 in +10.7% Too tall
Section width 12.01 in 12.50 in +0.49 in Computed difference
Sidewall height 4.80 in 8.50 in +3.70 in Computed difference
Circumference 99.29 in 109.96 in +10.7% Too tall
Speedo 0.0% +10.7% +10.7% Outside tolerance

Compare sizes

Looks valid
Looks valid
Units
✕ Out of toleranceDiameter +10.7% (+3.39 in) · US (~3%)
  • Out of tolerance · Diameter +10.7%.
  • Speedo @ 60: 60 mph → 66.4 mph.
  • Sidewall +3.70 in · Width +0.49 in.
Diameter+10.7%+3.39 in
Speedo @ 60+10.7%60 mph → 66.4 mph
Sidewall+3.70 inWidth +0.49 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
31.61 in 35.00 in+3.39 in
Sidewall
4.80 in 8.50 in+3.70 in
Width
12.01 in 12.50 in+0.49 in
Circumference
99.29 in 109.96 in+10.7%
Revs / mile
638 576
Speedo @ 60
60 mph 66.4 mph+10.7%
Δ⌀ +86.2 mm
  • Current — 305/40 R22
  • New — 35x12.50 R18
  • Grounded to the road: the axle rises +1.70 in.

Result report

305/40 R22 35x12.50 R18 · Out of tolerance

Use this size when shopping: 35x12.50 R18

Use this size when shopping

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

Safe alternative sizes

SizeDiameterSpeedo @ 100Use this
−1″ 245/55R21+0.0%+0.0%
OE 305/40R22+0.0%+0.0%
+1″ 145/75R23-0.1%-0.1%
+2″ 215/45R24+0.0%+0.0%

305/40 R22 · 35x12.50 R18 · Methodology

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