235/55R19 vs 255/40R21
255/40R21 is 4.0 mm shorter than 235/55R19 in overall diameter (−0.5%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 255/40R21 fitted, the speedometer reads 100 km/h when you are doing 99.5 km/h.
Dimensions side by side
| 235/55R19 | 255/40R21 | |
|---|---|---|
| Overall diameter | 741 mm (29.2″) | 737 mm (29.0″) |
| Section width | 235 mm | 255 mm |
| Sidewall height | 129 mm | 102 mm |
| Rim | 19″ | 21″ |
| Revolutions per km | 430 | 432 |
| In stock | 126 tires from $178.00 | 23 tires from $298.00 |
What changes
- Overall diameter: 255/40R21 is 4.0 mm shorter (−0.5%).
- Speedometer: reads 100 km/h at an actual 99.5 km/h with 255/40R21.
- 255/40R21 is 20 mm wider, so check clearance and the recommended rim width.
- Wheel size changes from 19″ to 21″: 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 235/55R19
Vehicles that use 255/40R21
See every alternate size for 235/55R19
Frequently asked questions
Can I use 255/40R21 instead of 235/55R19?
Usually, yes: 255/40R21 is within 3% of the overall diameter of 235/55R19 (−0.5%). 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 235/55R19 and 255/40R21?
With 255/40R21 instead of 235/55R19, the speedometer shows 100 km/h when you are actually doing 99.5 km/h.
Which vehicles came with both 235/55R19 and 255/40R21?
Both sizes were original equipment, on different trims or packages, on the 2017, 2021–2024 Audi Q5, 2023–2024 Maserati Grecale, 2024 Alfa Romeo Stelvio, 2018–2022 Volvo XC60.