285/50 R20
What size is 285/50 R20?
285/50 R20 has an overall diameter of about 31.22 in, a section width of 11.22 in and a sidewall height of 5.61 in. It turns roughly 646 times per mile. Below are the exact figures plus in-tolerance plus/minus sizes you can switch to safely.
- Overall diameter: 31.22 in.
- Section width: 11.22 in.
- Sidewall height: 5.61 in.
- Revolutions: 401 /km · 646 /mi.
- In-tolerance sizes: 31x10.50 R15 (-0.7%).
Fitment verdict
31x10.50 R15 stays within the configured tolerance for 285/50 R20: -0.7% diameter and -0.7% speedometer effect.
| Metric | This size: 285/50 R20 | Alternative: 31x10.50 R15 | Difference | Verdict |
|---|---|---|---|---|
| Overall diameter | 31.22 in | 31.00 in | -0.7% | Within tolerance |
| Section width | 11.22 in | 10.50 in | -0.72 in | Computed difference |
| Sidewall height | 5.61 in | 8.00 in | +2.39 in | Computed difference |
| Circumference | 98.08 in | 97.39 in | -0.7% | Within tolerance |
| Speedo | 0.0% | -0.7% | -0.7% | Within tolerance |
Seasonal check
Planning a long summer drive?
Use the budget and running-cost tools before a trip, especially if the current tyres are worn or the replacement size changes diameter.
Specification
| Overall diameter | 31.22 in |
|---|---|
| Section width | 11.22 in |
| Sidewall height | 5.61 in |
| Circumference | 98.08 in |
| Revolutions | 401 /km · 646 /mi |
In-tolerance sizes
Alternative sizes that stay within the safe diameter tolerance:
| Size | Diameter | Speedo | Verdict |
|---|---|---|---|
| 31x10.50 R15 | -0.7% | -0.7% | ✓ OK |
| 31x10.50 R16 | -0.7% | -0.7% | ✓ OK |
| 285/60 R18 | +0.8% | +0.8% | ✓ OK |
| 285/40 R22 | -0.8% | -0.8% | ✓ OK |
| 275/55 R19 | -1.0% | -1.0% | ✓ OK |
| 265/65 R18 | +1.1% | +1.1% | ✓ OK |
| 265/70 R17 | +1.2% | +1.2% | ✓ OK |
| 305/40 R22 | +1.2% | +1.2% | ✓ OK |
| 275/45 R21 | -1.5% | -1.5% | ✓ OK |
| 275/45 R22 | +1.7% | +1.7% | ✓ OK |
| 265/70 R16 | -2.0% | -2.0% | ✓ OK |
| 265/65 R17 | -2.1% | -2.1% | ✓ OK |
Compare sizes
- Within tolerance · Diameter -0.7%.
- Speedo @ 60: 60 mph → 59.6 mph.
- Sidewall +2.39 in · Width -0.72 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
- 31.22 in 31.00 in-0.22 in
- Sidewall
- 5.61 in 8.00 in+2.39 in
- Width
- 11.22 in 10.50 in-0.72 in
- Circumference
- 98.08 in 97.39 in-0.7%
- Revs / mile
- 646 651
- Speedo @ 60
- 60 mph 59.6 mph-0.7%
- Current —
285/50 R20 - New —
31x10.50 R15 - Grounded to the road: the axle rises -0.11 in.
Result report
285/50 R20 31x10.50 R15 · Within tolerance
Use this size when shopping: 31x10.50 R15
Geometric estimate. Always verify physical clearance (arches, suspension, brakes) before fitting.
Safe alternative sizes
| Size | Diameter | Speedo @ 100 | Use this |
|---|---|---|---|
−1″ 345/45R19 | +0.0% | +0.0% | |
OE 285/50R20 | +0.0% | +0.0% | |
+1″ 325/40R21 | +0.1% | +0.1% | |
+2″ 195/60R22 | -0.0% | -0.0% |
More tools
- How to read a tire size
- Plus sizing guide
- Speedometer error guide
- 285mm Section width guide
- /50 Aspect ratio guide
- Rim diameter 20"
- Load index chart
- Speed rating chart
- Rim width and tyre fitment guide
- Wheel offset guide
- Wheel spacers guide
- Tyre pressure for heavy loads and towing
What changed
- Reviewed deterministic geometry, load/speed references, sitemap inclusion and localized page shell.