245/70 R17 vs 31x10.50 R15

31x10.50 R15 stays within the configured tolerance for 245/70 R17: +1.6% diameter and +1.6% speedometer effect.

Geometric comparison

31x10.50 R15 stays within the configured tolerance for 245/70 R17: +1.6% diameter and +1.6% speedometer effect.

Geometric comparison
Metric	This size: 245/70 R17	Alternative: 31x10.50 R15	Difference	Verdict
Overall diameter	30.50 in	31.00 in	+1.6%	Within tolerance
Section width	9.65 in	10.50 in	+0.85 in	Computed difference
Sidewall height	6.75 in	8.00 in	+1.25 in	Computed difference
Circumference	95.83 in	97.39 in	+1.6%	Within tolerance
Speedo	0.0%	+1.6%	+1.6%	Within tolerance

Compare sizes

Current tireLooks valid

New tireLooks valid

Market

Units

High fitment riskWithin tolerance · Diameter +1.6% (+0.50 in) · US (~3%)

High fitment risk · This rating covers tire geometry only, not vehicle compatibility.
Diameter +1.6% · Ride-height change +0.25 in.
Speedometer reads low · 60 mph → 61.0 mph.
Sidewall +1.25 in · Width +0.85 in.

Diameter+1.6%+0.50 in

Speedo @ 60+1.6%60 mph → 61.0 mph

Sidewall+1.25 inWidth +0.85 in

Ride-height change+0.25 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: 30.50 in 31.00 in+0.50 in
Sidewall: 6.75 in 8.00 in+1.25 in
Width: 9.65 in 10.50 in+0.85 in
Circumference: 95.83 in 97.39 in+1.6%
Revs / mile: 661 651
Speedo @ 60: 60 mph 61.0 mph+1.6%
Ride-height change: 0.00 in +0.25 in
True distance per 100 indicated: 100 mi 101.6 mi+1.6%

Current — 245/70 R17
New — 31x10.50 R15
Grounded to the road: the axle rises +0.25 in.

Result report

245/70 R17 31x10.50 R15 · High fitment risk · Within tolerance

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Markdown link

[245/70 R17 vs 31x10.50 R15 Tire size comparison](https://tirefitlab.com/tire-size-calculator/?from=245%2F70+R17&to=31x10.50+R15&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 `245/70R17`	+0.0%	+0.0%
+1″ `265/60R18`	+0.1%	+0.1%

245/70 R17 · 31x10.50 R15 · Methodology

Technical check: 2026-06-28

What changed

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

Methodology