255/55R18 vs 265/45R20
265/45R20 is 9.0 mm taller than 255/55R18 in overall diameter (+1.2%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 265/45R20 fitted, the speedometer reads 100 km/h when you are doing 101.2 km/h.
Dimensions side by side
| 255/55R18 | 265/45R20 | |
|---|---|---|
| Overall diameter | 738 mm (29.1″) | 747 mm (29.4″) |
| Section width | 255 mm | 265 mm |
| Sidewall height | 140 mm | 119 mm |
| Rim | 18″ | 20″ |
| Revolutions per km | 431 | 426 |
| In stock | 27 tires from $160.00 | 38 tires from $162.00 |
What changes
- Overall diameter: 265/45R20 is 9.0 mm taller (+1.2%).
- Speedometer: reads 100 km/h at an actual 101.2 km/h with 265/45R20.
- 265/45R20 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 255/55R18
Vehicles that use 265/45R20
See every alternate size for 255/55R18
Frequently asked questions
Can I use 265/45R20 instead of 255/55R18?
Usually, yes: 265/45R20 is within 3% of the overall diameter of 255/55R18 (+1.2%). 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 255/55R18 and 265/45R20?
With 265/45R20 instead of 255/55R18, the speedometer shows 100 km/h when you are actually doing 101.2 km/h.
Which vehicles came with both 255/55R18 and 265/45R20?
Both sizes were original equipment, on different trims or packages, on the 2015–2021 Porsche Macan, 2016 Mercedes-Benz GLE300d, 2015 Mercedes-Benz ML250, 2007–2011 Mercedes-Benz R350, 2007 Mercedes-Benz ML320, 2007 Mercedes-Benz R500.