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.

Geometric comparison

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

Geometric comparison
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

Current tireLooks valid

New tireLooks valid

Market

Units

Not recommendedOut of tolerance · Diameter +12.8% (+4.19 in) · US (~3%)

Not recommended · This rating covers tire geometry only, not vehicle compatibility.
Diameter +12.8% · Ride-height change +2.10 in.
Speedometer reads low · 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

Ride-height change+2.10 inDiameter ÷ 2

How this result is calculated

Computed from nominal tire-size geometry: diameter, circumference and speedometer error. It does not check vehicle placard approval, load/speed rating, rim-width range, wheel-arch, suspension or brake clearance.

Methodology

Before fitting

Check the vehicle placard and owner’s manual first.
Match or exceed the required load index and speed rating.
Confirm rim-width range, bolt pattern, hub bore, offset and fasteners.
Inspect wheel-arch, suspension and brake clearance under real vehicle load.
Check TPMS, cold pressure and local roadworthiness rules.

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%
Ride-height change: 0.00 in +2.10 in
True distance per 100 indicated: 100 mi 112.8 mi+12.8%

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 · Not recommended · Out of tolerance

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Markdown link

[305/45 R22 vs 37x13.50 R20 Tire size comparison](https://tirefitlab.com/tire-size-calculator/?from=305%2F45+R22&to=37x13.50+R20&market=us)

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

In-tolerance alternative sizes

In-tolerance alternative sizes
Size	Diameter	Speedo @ 100	Use this
OE `305/45R22`	+0.0%	+0.0%

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

Technical check: 2026-06-28

What changed

Checked generated routes, metadata, sitemap inclusion and localized page rendering.

Methodology