285/65 R18
What size is 285/65 R18?
285/65 R18 has an overall diameter of about 32.59 in, a section width of 11.22 in and a sidewall height of 7.29 in. It turns roughly 619 times per mile. Below are the exact figures plus in-tolerance plus/minus sizes you can switch to safely.
- Overall diameter: 32.59 in.
- Section width: 11.22 in.
- Sidewall height: 7.29 in.
- Revolutions: 385 /km · 619 /mi.
- In-tolerance sizes: 305/45 R22 (+0.7%).
Fitment verdict
305/45 R22 stays within the configured tolerance for 285/65 R18: +0.7% diameter and +0.7% speedometer effect.
| Metric | This size: 285/65 R18 | Alternative: 305/45 R22 | Difference | Verdict |
|---|---|---|---|---|
| Overall diameter | 32.59 in | 32.81 in | +0.7% | Within tolerance |
| Section width | 11.22 in | 12.01 in | +0.79 in | Computed difference |
| Sidewall height | 7.29 in | 5.40 in | -1.89 in | Computed difference |
| Circumference | 102.37 in | 103.07 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 | 32.59 in |
|---|---|
| Section width | 11.22 in |
| Sidewall height | 7.29 in |
| Circumference | 102.37 in |
| Revolutions | 385 /km · 619 /mi |
In-tolerance sizes
Alternative sizes that stay within the safe diameter tolerance:
| Size | Diameter | Speedo | Verdict |
|---|---|---|---|
| 305/45 R22 | +0.7% | +0.7% | ✓ OK |
| 33x12.50 R15 | +1.3% | +1.3% | ✓ OK |
| 33x12.50 R16 | +1.3% | +1.3% | ✓ OK |
| 33x12.50 R18 | +1.3% | +1.3% | ✓ OK |
| 285/45 R22 | -1.5% | -1.5% | ✓ OK |
| 275/65 R18 | -1.6% | -1.6% | ✓ OK |
| 275/70 R18 | +1.8% | +1.8% | ✓ OK |
| 275/55 R20 | -2.1% | -2.1% | ✓ OK |
| 275/45 R22 | -2.6% | -2.6% | ✓ OK |
Compare sizes
- Within tolerance · Diameter +0.7%.
- Speedo @ 60: 60 mph → 60.4 mph.
- Sidewall -1.89 in · Width +0.79 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
- 32.59 in 32.81 in+0.22 in
- Sidewall
- 7.29 in 5.40 in-1.89 in
- Width
- 11.22 in 12.01 in+0.79 in
- Circumference
- 102.37 in 103.07 in+0.7%
- Revs / mile
- 619 615
- Speedo @ 60
- 60 mph 60.4 mph+0.7%
- Current —
285/65 R18 - New —
305/45 R22 - Grounded to the road: the axle rises +0.11 in.
Result report
285/65 R18 305/45 R22 · Within tolerance
Use this size when shopping: 305/45 R22
Geometric estimate. Always verify physical clearance (arches, suspension, brakes) before fitting.
Safe alternative sizes
| Size | Diameter | Speedo @ 100 | Use this |
|---|---|---|---|
−1″ 305/65R17 | +0.1% | +0.1% | |
OE 285/65R18 | +0.0% | +0.0% | |
+1″ 345/50R19 | -0.0% | -0.0% | |
+2″ 355/45R20 | -0.0% | -0.0% |
More tools
- How to read a tire size
- Plus sizing guide
- Speedometer error guide
- 285mm Section width guide
- /65 Aspect ratio guide
- Rim diameter 18"
- 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.