275/70 R18
What size is 275/70 R18?
275/70 R18 has an overall diameter of about 33.16 in, a section width of 10.83 in and a sidewall height of 7.58 in. It turns roughly 608 times per mile. Below are the exact figures plus in-tolerance plus/minus sizes you can switch to safely.
- Overall diameter: 33.16 in.
- Section width: 10.83 in.
- Sidewall height: 7.58 in.
- Revolutions: 378 /km · 608 /mi.
- In-tolerance sizes: 33x12.50 R15 (-0.5%).
Fitment verdict
33x12.50 R15 stays within the configured tolerance for 275/70 R18: -0.5% diameter and -0.5% speedometer effect.
| Metric | This size: 275/70 R18 | Alternative: 33x12.50 R15 | Difference | Verdict |
|---|---|---|---|---|
| Overall diameter | 33.16 in | 33.00 in | -0.5% | Within tolerance |
| Section width | 10.83 in | 12.50 in | +1.67 in | Computed difference |
| Sidewall height | 7.58 in | 9.00 in | +1.42 in | Computed difference |
| Circumference | 104.17 in | 103.67 in | -0.5% | Within tolerance |
| Speedo | 0.0% | -0.5% | -0.5% | 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 | 33.16 in |
|---|---|
| Section width | 10.83 in |
| Sidewall height | 7.58 in |
| Circumference | 104.17 in |
| Revolutions | 378 /km · 608 /mi |
In-tolerance sizes
Alternative sizes that stay within the safe diameter tolerance:
| Size | Diameter | Speedo | Verdict |
|---|---|---|---|
| 33x12.50 R15 | -0.5% | -0.5% | ✓ OK |
| 33x12.50 R16 | -0.5% | -0.5% | ✓ OK |
| 33x12.50 R18 | -0.5% | -0.5% | ✓ OK |
| 305/45 R22 | -1.1% | -1.1% | ✓ OK |
| 285/65 R18 | -1.7% | -1.7% | ✓ OK |
Compare sizes
- Within tolerance · Diameter -0.5%.
- Speedo @ 60: 60 mph → 59.7 mph.
- Sidewall +1.42 in · Width +1.67 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
- 33.16 in 33.00 in-0.16 in
- Sidewall
- 7.58 in 9.00 in+1.42 in
- Width
- 10.83 in 12.50 in+1.67 in
- Circumference
- 104.17 in 103.67 in-0.5%
- Revs / mile
- 608 611
- Speedo @ 60
- 60 mph 59.7 mph-0.5%
- Current —
275/70 R18 - New —
33x12.50 R15 - Grounded to the road: the axle rises -0.08 in.
Result report
275/70 R18 33x12.50 R15 · Within tolerance
Use this size when shopping: 33x12.50 R15
Geometric estimate. Always verify physical clearance (arches, suspension, brakes) before fitting.
Safe alternative sizes
| Size | Diameter | Speedo @ 100 | Use this |
|---|---|---|---|
−1″ 315/65R17 | -0.1% | -0.1% | |
OE 275/70R18 | +0.0% | +0.0% | |
+1″ 225/80R19 | +0.0% | +0.0% | |
+2″ 335/50R20 | +0.1% | +0.1% |
More tools
- How to read a tire size
- Plus sizing guide
- Speedometer error guide
- 275mm Section width guide
- /70 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.