31x10.50 R15 vs 285/65 R18
31x10.50 R15 vs 285/65 R18
285/65 R18 is outside the configured tolerance for 31x10.50 R15: +5.1% diameter and +5.1% speedometer effect.
Geometric comparison
285/65 R18 is outside the configured tolerance for 31x10.50 R15: +5.1% diameter and +5.1% speedometer effect.
| Metric | This size: 31x10.50 R15 | Alternative: 285/65 R18 | Difference | Verdict |
|---|---|---|---|---|
| Overall diameter | 31.00 in | 32.59 in | +5.1% | Too tall |
| Section width | 10.50 in | 11.22 in | +0.72 in | Computed difference |
| Sidewall height | 8.00 in | 7.29 in | -0.71 in | Computed difference |
| Circumference | 97.39 in | 102.37 in | +5.1% | Too tall |
| Speedo | 0.0% | +5.1% | +5.1% | Outside tolerance |
Compare sizes
Looks valid
Looks valid
Units
High fitment riskOut of tolerance · Diameter +5.1% (+1.59 in) · US (~3%)
- High fitment risk · This rating covers tire geometry only, not vehicle compatibility.
- Diameter +5.1% · Ride-height change +0.79 in.
- Speedometer reads low · 60 mph → 63.1 mph.
- Sidewall -0.71 in · Width +0.72 in.
Diameter+5.1%+1.59 in
Speedo @ 60+5.1%60 mph → 63.1 mph
Sidewall-0.71 inWidth +0.72 in
Ride-height change+0.79 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.
MethodologyBefore 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
- 31.00 in 32.59 in+1.59 in
- Sidewall
- 8.00 in 7.29 in-0.71 in
- Width
- 10.50 in 11.22 in+0.72 in
- Circumference
- 97.39 in 102.37 in+5.1%
- Revs / mile
- 651 619
- Speedo @ 60
- 60 mph 63.1 mph+5.1%
- Ride-height change
- 0.00 in +0.79 in
- True distance per 100 indicated
- 100 mi 105.1 mi+5.1%
- Current —
31x10.50 R15 - New —
285/65 R18 - Grounded to the road: the axle rises +0.79 in.
Result report
31x10.50 R15 285/65 R18 · High fitment risk · Out of tolerance
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Geometric estimate. Always verify physical clearance (arches, suspension, brakes) before fitting.
In-tolerance alternative sizes
| Size | Diameter | Speedo @ 100 | Use this |
|---|---|---|---|
OE 255/80R15 | +0.2% | +0.2% |
31x10.50 R15 · 285/65 R18 · Methodology
- Technical check
- 2026-06-28
What changed
- Checked generated routes, metadata, sitemap inclusion and localized page rendering.