215/50R17 vs 235/40R18
235/40R18 is 2.0 mm shorter than 215/50R17 in overall diameter (−0.3%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 235/40R18 fitted, the speedometer reads 100 km/h when you are doing 99.7 km/h.
Dimensions side by side
| 215/50R17 | 235/40R18 | |
|---|---|---|
| Overall diameter | 647 mm (25.5″) | 645 mm (25.4″) |
| Section width | 215 mm | 235 mm |
| Sidewall height | 108 mm | 94 mm |
| Rim | 17″ | 18″ |
| Revolutions per km | 492 | 494 |
| In stock | 33 tires from $105.00 | 45 tires from $110.00 |
What changes
- Overall diameter: 235/40R18 is 2.0 mm shorter (−0.3%).
- Speedometer: reads 100 km/h at an actual 99.7 km/h with 235/40R18.
- 235/40R18 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 215/50R17
Vehicles that use 235/40R18
See every alternate size for 215/50R17
Frequently asked questions
Can I use 235/40R18 instead of 215/50R17?
Usually, yes: 235/40R18 is within 3% of the overall diameter of 215/50R17 (−0.3%). 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 215/50R17 and 235/40R18?
With 235/40R18 instead of 215/50R17, the speedometer shows 100 km/h when you are actually doing 99.7 km/h.
Which vehicles came with both 215/50R17 and 235/40R18?
Both sizes were original equipment, on different trims or packages, on the 2012–2017 Ford Focus, 2012–2017 Volvo S60, 2015–2017 Volvo V60.