275/45R20 vs 315/35R21
315/35R21 is 2.0 mm shorter than 275/45R20 in overall diameter (−0.3%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 315/35R21 fitted, the speedometer reads 100 km/h when you are doing 99.7 km/h.
Dimensions side by side
| 275/45R20 | 315/35R21 | |
|---|---|---|
| Overall diameter | 756 mm (29.8″) | 754 mm (29.7″) |
| Section width | 275 mm | 315 mm |
| Sidewall height | 124 mm | 110 mm |
| Rim | 20″ | 21″ |
| Revolutions per km | 421 | 422 |
| In stock | 50 tires from $166.00 | 10 tires from $322.00 |
What changes
- Overall diameter: 315/35R21 is 2.0 mm shorter (−0.3%).
- Speedometer: reads 100 km/h at an actual 99.7 km/h with 315/35R21.
- 315/35R21 is 40 mm wider, so check clearance and the recommended rim width.
- Wheel size changes from 20″ to 21″: you need wheels in the new size.
- Choose a load index at least as high as the one on your door placard.
Vehicles that came with both sizes
Vehicles that use 275/45R20
Vehicles that use 315/35R21
See every alternate size for 275/45R20
Frequently asked questions
Can I use 315/35R21 instead of 275/45R20?
Usually, yes: 315/35R21 is within 3% of the overall diameter of 275/45R20 (−0.3%). Use wheels of the right size and width, match or exceed the original load index, and check clearance at full steering lock.
How much does the speedometer change between 275/45R20 and 315/35R21?
With 315/35R21 instead of 275/45R20, the speedometer shows 100 km/h when you are actually doing 99.7 km/h.
Which vehicles came with both 275/45R20 and 315/35R21?
Both sizes were original equipment, on different trims or packages, on the 2019–2024 BMW X5, 2020–2024 BMW X6, 2019–2023 Porsche Cayenne.