245/45 R20
What size is 245/45 R20?
245/45 R20 has an overall diameter of about 28.68 in, a section width of 9.65 in and a sidewall height of 4.34 in. It turns roughly 703 times per mile. Below are the exact figures plus in-tolerance plus/minus sizes you can switch to safely.
- Overall diameter: 28.68 in.
- Section width: 9.65 in.
- Sidewall height: 4.34 in.
- Revolutions: 437 /km · 703 /mi.
- In-tolerance sizes: 275/40 R20 (-0.1%).
Fitment verdict
275/40 R20 stays within the configured tolerance for 245/45 R20: -0.1% diameter and -0.1% speedometer effect.
| Metric | This size: 245/45 R20 | Alternative: 275/40 R20 | Difference | Verdict |
|---|---|---|---|---|
| Overall diameter | 28.68 in | 28.66 in | -0.1% | Within tolerance |
| Section width | 9.65 in | 10.83 in | +1.18 in | Computed difference |
| Sidewall height | 4.34 in | 4.33 in | -0.01 in | Computed difference |
| Circumference | 90.10 in | 90.04 in | -0.1% | Within tolerance |
| Speedo | 0.0% | -0.1% | -0.1% | 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 | 28.68 in |
|---|---|
| Section width | 9.65 in |
| Sidewall height | 4.34 in |
| Circumference | 90.10 in |
| Revolutions | 437 /km · 703 /mi |
In-tolerance sizes
Alternative sizes that stay within the safe diameter tolerance:
| Size | Diameter | Speedo | Verdict |
|---|---|---|---|
| 275/40 R20 | -0.1% | -0.1% | ✓ OK |
| 275/45 R19 | +0.2% | +0.2% | ✓ OK |
| 225/65 R17 | -0.6% | -0.6% | ✓ OK |
| 235/65 R17 | +1.2% | +1.2% | ✓ OK |
| 255/45 R20 | +1.2% | +1.2% | ✓ OK |
| 255/50 R19 | +1.2% | +1.2% | ✓ OK |
| 255/55 R18 | +1.3% | +1.3% | ✓ OK |
| 285/45 R19 | +1.5% | +1.5% | ✓ OK |
| 235/60 R18 | +1.5% | +1.5% | ✓ OK |
| 235/50 R19 | -1.5% | -1.5% | ✓ OK |
| 295/35 R21 | +1.6% | +1.6% | ✓ OK |
| 235/55 R19 | +1.7% | +1.7% | ✓ OK |
Compare sizes
- Within tolerance · Diameter -0.1%.
- Speedo @ 60: 60 mph → 60.0 mph.
- Sidewall -0.01 in · Width +1.18 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
- 28.68 in 28.66 in-0.02 in
- Sidewall
- 4.34 in 4.33 in-0.01 in
- Width
- 9.65 in 10.83 in+1.18 in
- Circumference
- 90.10 in 90.04 in-0.1%
- Revs / mile
- 703 704
- Speedo @ 60
- 60 mph 60.0 mph-0.1%
- Current —
245/45 R20 - New —
275/40 R20 - Grounded to the road: the axle rises -0.01 in.
Result report
245/45 R20 275/40 R20 · Within tolerance
Use this size when shopping: 275/40 R20
Geometric estimate. Always verify physical clearance (arches, suspension, brakes) before fitting.
Safe alternative sizes
| Size | Diameter | Speedo @ 100 | Use this |
|---|---|---|---|
−1″ 205/60R19 | +0.0% | +0.0% | |
OE 245/45R20 | +0.0% | +0.0% | |
+1″ 195/50R21 | -0.0% | -0.0% | |
+2″ 155/55R22 | +0.1% | +0.1% |
More tools
- How to read a tire size
- Plus sizing guide
- Speedometer error guide
- 245mm Section width guide
- /45 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.