265/45 R21
What size is 265/45 R21?
265/45 R21 has an overall diameter of about 30.39 in, a section width of 10.43 in and a sidewall height of 4.69 in. It turns roughly 664 times per mile. Below are the exact figures plus in-tolerance plus/minus sizes you can switch to safely.
- Overall diameter: 30.39 in.
- Section width: 10.43 in.
- Sidewall height: 4.69 in.
- Revolutions: 412 /km · 664 /mi.
- In-tolerance sizes: 265/50 R20 (+0.1%).
Fitment verdict
265/50 R20 stays within the configured tolerance for 265/45 R21: +0.1% diameter and +0.1% speedometer effect.
| Metric | This size: 265/45 R21 | Alternative: 265/50 R20 | Difference | Verdict |
|---|---|---|---|---|
| Overall diameter | 30.39 in | 30.43 in | +0.1% | Within tolerance |
| Section width | 10.43 in | 10.43 in | 0.00 in | Computed difference |
| Sidewall height | 4.69 in | 5.22 in | +0.52 in | Computed difference |
| Circumference | 95.47 in | 95.61 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 | 30.39 in |
|---|---|
| Section width | 10.43 in |
| Sidewall height | 4.69 in |
| Circumference | 95.47 in |
| Revolutions | 412 /km · 664 /mi |
In-tolerance sizes
Alternative sizes that stay within the safe diameter tolerance:
| Size | Diameter | Speedo | Verdict |
|---|---|---|---|
| 265/50 R20 | +0.1% | +0.1% | ✓ OK |
| 265/40 R22 | -0.1% | -0.1% | ✓ OK |
| 245/70 R17 | +0.4% | +0.4% | ✓ OK |
| 265/60 R18 | +0.4% | +0.4% | ✓ OK |
| 245/65 R18 | +0.5% | +0.5% | ✓ OK |
| 265/65 R17 | +0.6% | +0.6% | ✓ OK |
| 265/70 R16 | +0.7% | +0.7% | ✓ OK |
| 255/65 R17 | -1.1% | -1.1% | ✓ OK |
| 255/50 R20 | -1.2% | -1.2% | ✓ OK |
| 275/45 R21 | +1.2% | +1.2% | ✓ OK |
| 235/65 R18 | -1.2% | -1.2% | ✓ OK |
| 235/70 R17 | -1.4% | -1.4% | ✓ OK |
Compare sizes
- Within tolerance · Diameter +0.1%.
- Speedo @ 60: 60 mph → 60.1 mph.
- Sidewall +0.52 in · Width +0.00 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
- 30.39 in 30.43 in+0.04 in
- Sidewall
- 4.69 in 5.22 in+0.52 in
- Width
- 10.43 in 10.43 in+0.00 in
- Circumference
- 95.47 in 95.61 in+0.1%
- Revs / mile
- 664 663
- Speedo @ 60
- 60 mph 60.1 mph+0.1%
- Current —
265/45 R21 - New —
265/50 R20 - Grounded to the road: the axle rises +0.02 in.
Result report
265/45 R21 265/50 R20 · Within tolerance
Use this size when shopping: 265/50 R20
Geometric estimate. Always verify physical clearance (arches, suspension, brakes) before fitting.
Safe alternative sizes
| Size | Diameter | Speedo @ 100 | Use this |
|---|---|---|---|
−1″ 165/80R20 | +0.0% | +0.0% | |
OE 265/45R21 | +0.0% | +0.0% | |
+1″ 355/30R22 | -0.0% | -0.0% | |
+2″ 125/75R23 | -0.0% | -0.0% |
More tools
- How to read a tire size
- Plus sizing guide
- Speedometer error guide
- 265mm Section width guide
- /45 Aspect ratio guide
- Rim diameter 21"
- 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.