235/65R17 vs 255/55R18
255/55R18 is 1.0 mm taller than 235/65R17 in overall diameter (+0.1%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 255/55R18 fitted, the speedometer reads 100 km/h when you are doing 100.1 km/h.
Dimensions side by side
| 235/65R17 | 255/55R18 | |
|---|---|---|
| Overall diameter | 737 mm (29.0″) | 738 mm (29.1″) |
| Section width | 235 mm | 255 mm |
| Sidewall height | 153 mm | 140 mm |
| Rim | 17″ | 18″ |
| Revolutions per km | 432 | 431 |
| In stock | 76 tires from $139.00 | 27 tires from $160.00 |
What changes
- Overall diameter: 255/55R18 is 1.0 mm taller (+0.1%).
- Speedometer: reads 100 km/h at an actual 100.1 km/h with 255/55R18.
- 255/55R18 is 20 mm wider, so check clearance and the recommended rim width.
- Wheel size changes from 17″ to 18″: 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 235/65R17
Vehicles that use 255/55R18
See every alternate size for 235/65R17
Frequently asked questions
Can I use 255/55R18 instead of 235/65R17?
Usually, yes: 255/55R18 is within 3% of the overall diameter of 235/65R17 (+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 235/65R17 and 255/55R18?
With 255/55R18 instead of 235/65R17, the speedometer shows 100 km/h when you are actually doing 100.1 km/h.
Which vehicles came with both 235/65R17 and 255/55R18?
Both sizes were original equipment, on different trims or packages, on the 2004–2006, 2008–2010 Porsche Cayenne, 2006–2007 Mercedes-Benz ML350, 2006–2007 Mercedes-Benz R350, 2007 Mercedes-Benz ML320, 2007 Mercedes-Benz R320, 2003–2006 BMW X5.