235/60R18 vs 255/45R20
255/45R20 is 1.0 mm shorter than 235/60R18 in overall diameter (−0.1%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 255/45R20 fitted, the speedometer reads 100 km/h when you are doing 99.9 km/h.
Dimensions side by side
| 235/60R18 | 255/45R20 | |
|---|---|---|
| Overall diameter | 739 mm (29.1″) | 738 mm (29.1″) |
| Section width | 235 mm | 255 mm |
| Sidewall height | 141 mm | 115 mm |
| Rim | 18″ | 20″ |
| Revolutions per km | 431 | 431 |
| In stock | 102 tires from $145.00 | 81 tires from $173.00 |
What changes
- Overall diameter: 255/45R20 is 1.0 mm shorter (−0.1%).
- Speedometer: reads 100 km/h at an actual 99.9 km/h with 255/45R20.
- 255/45R20 is 20 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 235/60R18
Vehicles that use 255/45R20
See every alternate size for 235/60R18
Frequently asked questions
Can I use 255/45R20 instead of 235/60R18?
Usually, yes: 255/45R20 is within 3% of the overall diameter of 235/60R18 (−0.1%). 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 235/60R18 and 255/45R20?
With 255/45R20 instead of 235/60R18, the speedometer shows 100 km/h when you are actually doing 99.9 km/h.
Which vehicles came with both 235/60R18 and 255/45R20?
Both sizes were original equipment, on different trims or packages, on the 2016–2024 Mercedes-Benz GLC300, 2023–2024 Lexus RZ, 2014–2022 Volvo XC60, 2018–2022 Alfa Romeo Stelvio, 2018–2021 Mercedes-Benz GLC350e, 2009–2019 Ford Flex.