235/40R18 vs 255/30R19
255/30R19 is 9.0 mm shorter than 235/40R18 in overall diameter (−1.4%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 255/30R19 fitted, the speedometer reads 100 km/h when you are doing 98.6 km/h.
Dimensions side by side
| 235/40R18 | 255/30R19 | |
|---|---|---|
| Overall diameter | 645 mm (25.4″) | 636 mm (25.0″) |
| Section width | 235 mm | 255 mm |
| Sidewall height | 94 mm | 77 mm |
| Rim | 18″ | 19″ |
| Revolutions per km | 494 | 500 |
| In stock | 45 tires from $110.00 | 7 tires from $257.00 |
What changes
- Overall diameter: 255/30R19 is 9.0 mm shorter (−1.4%).
- Speedometer: reads 100 km/h at an actual 98.6 km/h with 255/30R19.
- 255/30R19 is 20 mm wider, so check clearance and the recommended rim width.
- Wheel size changes from 18″ to 19″: 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 235/40R18
Vehicles that use 255/30R19
See every alternate size for 235/40R18
Frequently asked questions
Can I use 255/30R19 instead of 235/40R18?
Usually, yes: 255/30R19 is within 3% of the overall diameter of 235/40R18 (−1.4%). 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 235/40R18 and 255/30R19?
With 255/30R19 instead of 235/40R18, the speedometer shows 100 km/h when you are actually doing 98.6 km/h.
Which vehicles came with both 235/40R18 and 255/30R19?
Both sizes were original equipment, on different trims or packages, on the 2014–2017 Mercedes-Benz E 550, 2015–2017 Mercedes-Benz E400, 2008–2016 Mercedes-Benz C63, 2014–2015 Mercedes-Benz E350.