TireFitLab

305/45 R22 vs 37x13.50 R20

305/45 R22 vs 37x13.50 R20

37x13.50 R20 is outside the configured tolerance for 305/45 R22: +12.8% diameter and +12.8% speedometer effect.

Fitment verdict

37x13.50 R20 is outside the configured tolerance for 305/45 R22: +12.8% diameter and +12.8% speedometer effect.

Metric This size: 305/45 R22 Alternative: 37x13.50 R20 Difference Verdict
Overall diameter 32.81 in 37.00 in +12.8% Too tall
Section width 12.01 in 13.50 in +1.49 in Computed difference
Sidewall height 5.40 in 8.50 in +3.10 in Computed difference
Circumference 103.07 in 116.24 in +12.8% Too tall
Speedo 0.0% +12.8% +12.8% Outside tolerance

Compare sizes

Looks valid
Looks valid
Units
✕ Out of toleranceDiameter +12.8% (+4.19 in) · US (~3%)
  • Out of tolerance · Diameter +12.8%.
  • Speedo @ 60: 60 mph → 67.7 mph.
  • Sidewall +3.10 in · Width +1.49 in.
Diameter+12.8%+4.19 in
Speedo @ 60+12.8%60 mph → 67.7 mph
Sidewall+3.10 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
32.81 in 37.00 in+4.19 in
Sidewall
5.40 in 8.50 in+3.10 in
Width
12.01 in 13.50 in+1.49 in
Circumference
103.07 in 116.24 in+12.8%
Revs / mile
615 545
Speedo @ 60
60 mph 67.7 mph+12.8%
Δ⌀ +106.5 mm
  • Current — 305/45 R22
  • New — 37x13.50 R20
  • Grounded to the road: the axle rises +2.10 in.

Result report

305/45 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″ 215/70R21+0.1%+0.1%
OE 305/45R22+0.0%+0.0%
+1″ 355/35R23-0.1%-0.1%
+2″ 225/50R24+0.2%+0.2%

305/45 R22 · 37x13.50 R20 · Methodology

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