245/45R18 vs 255/35R20
255/35R20 is 9.0 mm taller than 245/45R18 in overall diameter (+1.3%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 255/35R20 fitted, the speedometer reads 100 km/h when you are doing 101.3 km/h.
Dimensions side by side
| 245/45R18 | 255/35R20 | |
|---|---|---|
| Overall diameter | 678 mm (26.7″) | 687 mm (27.0″) |
| Section width | 245 mm | 255 mm |
| Sidewall height | 110 mm | 89 mm |
| Rim | 18″ | 20″ |
| Revolutions per km | 469 | 463 |
| In stock | 50 tires from $118.00 | 12 tires from $129.00 |
What changes
- Overall diameter: 255/35R20 is 9.0 mm taller (+1.3%).
- Speedometer: reads 100 km/h at an actual 101.3 km/h with 255/35R20.
- 255/35R20 is 10 mm wider, so check clearance and the recommended rim width.
- Wheel size changes from 18″ to 20″: 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 245/45R18
Vehicles that use 255/35R20
See every alternate size for 245/45R18
Frequently asked questions
Can I use 255/35R20 instead of 245/45R18?
Usually, yes: 255/35R20 is within 3% of the overall diameter of 245/45R18 (+1.3%). 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 245/45R18 and 255/35R20?
With 255/35R20 instead of 245/45R18, the speedometer shows 100 km/h when you are actually doing 101.3 km/h.
Which vehicles came with both 245/45R18 and 255/35R20?
Both sizes were original equipment, on different trims or packages, on the 2020–2024 Cadillac CT5, 2022–2024 BMW 430i, 2022–2024 BMW M440i, 2014–2021 Jaguar F-Type, 2012–2018 Audi A6, 2009–2015 Jaguar XF.