235/45R17 vs 255/40R17
255/40R17 is 7.0 mm shorter than 235/45R17 in overall diameter (−1.1%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 255/40R17 fitted, the speedometer reads 100 km/h when you are doing 98.9 km/h.
Dimensions side by side
| 235/45R17 | 255/40R17 | |
|---|---|---|
| Overall diameter | 643 mm (25.3″) | 636 mm (25.0″) |
| Section width | 235 mm | 255 mm |
| Sidewall height | 106 mm | 102 mm |
| Rim | 17″ | 17″ |
| Revolutions per km | 495 | 500 |
| In stock | 21 tires from $119.00 | 5 tires from $225.00 |
What changes
- Overall diameter: 255/40R17 is 7.0 mm shorter (−1.1%).
- Speedometer: reads 100 km/h at an actual 98.9 km/h with 255/40R17.
- 255/40R17 is 20 mm wider, so check clearance and the recommended rim width.
- Choose a load index at least as high as the one on your door placard.
Vehicles that came with both sizes
Vehicles that use 235/45R17
Vehicles that use 255/40R17
See every alternate size for 235/45R17
Frequently asked questions
Can I use 255/40R17 instead of 235/45R17?
Usually, yes: 255/40R17 is within 3% of the overall diameter of 235/45R17 (−1.1%). 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 235/45R17 and 255/40R17?
With 255/40R17 instead of 235/45R17, the speedometer shows 100 km/h when you are actually doing 98.9 km/h.
Which vehicles came with both 235/45R17 and 255/40R17?
Both sizes were original equipment, on different trims or packages, on the 2010–2013 Mercedes-Benz E350, 1999–2003 BMW 540iA, 1999–2002 BMW 540i, 1993–1998 Toyota Supra.