TireFitLab

305/40 R22 vs 37x13.50 R20

305/40 R22 vs 37x13.50 R20

37x13.50 R20 is outside the configured tolerance for 305/40 R22: +17.1% diameter and +17.1% speedometer effect.

Fitment verdict

37x13.50 R20 is outside the configured tolerance for 305/40 R22: +17.1% diameter and +17.1% speedometer effect.

Metric This size: 305/40 R22 Alternative: 37x13.50 R20 Difference Verdict
Overall diameter 31.61 in 37.00 in +17.1% Too tall
Section width 12.01 in 13.50 in +1.49 in Computed difference
Sidewall height 4.80 in 8.50 in +3.70 in Computed difference
Circumference 99.29 in 116.24 in +17.1% Too tall
Speedo 0.0% +17.1% +17.1% Outside tolerance

Compare sizes

Looks valid
Looks valid
Units
✕ Out of toleranceDiameter +17.1% (+5.39 in) · US (~3%)
  • Out of tolerance · Diameter +17.1%.
  • Speedo @ 60: 60 mph → 70.2 mph.
  • Sidewall +3.70 in · Width +1.49 in.
Diameter+17.1%+5.39 in
Speedo @ 60+17.1%60 mph → 70.2 mph
Sidewall+3.70 inWidth +1.49 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 37.00 in+5.39 in
Sidewall
4.80 in 8.50 in+3.70 in
Width
12.01 in 13.50 in+1.49 in
Circumference
99.29 in 116.24 in+17.1%
Revs / mile
638 545
Speedo @ 60
60 mph 70.2 mph+17.1%
Δ⌀ +137.0 mm
  • Current — 305/40 R22
  • New — 37x13.50 R20
  • Grounded to the road: the axle rises +2.70 in.

Result report

305/40 R22 37x13.50 R20 · Out of tolerance

Use this size when shopping: 37x13.50 R20

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 · 37x13.50 R20 · Methodology

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