255/40R18 vs 285/35R18

285/35R18 is 4.0 mm shorter than 255/40R18 in overall diameter (−0.6%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 285/35R18 fitted, the speedometer reads 100 km/h when you are doing 99.4 km/h.

Dimensions side by side

	255/40R18	285/35R18
Overall diameter	661 mm (26.0″)	657 mm (25.9″)
Section width	255 mm	285 mm
Sidewall height	102 mm	100 mm
Rim	18″	18″
Revolutions per km	482	484
In stock	13 tires from $238.00	6 tires from $278.00

What changes

Overall diameter: 285/35R18 is 4.0 mm shorter (−0.6%).
Speedometer: reads 100 km/h at an actual 99.4 km/h with 285/35R18.
285/35R18 is 30 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 255/40R18

Vehicles that use 285/35R18

See every alternate size for 255/40R18

Frequently asked questions

Can I use 285/35R18 instead of 255/40R18?

Usually, yes: 285/35R18 is within 3% of the overall diameter of 255/40R18 (−0.6%). 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 255/40R18 and 285/35R18?

With 285/35R18 instead of 255/40R18, the speedometer shows 100 km/h when you are actually doing 99.4 km/h.

Which vehicles came with both 255/40R18 and 285/35R18?

Both sizes were original equipment, on different trims or packages, on the 2017–2021 Mercedes-Benz C63, 2007–2018 Mercedes-Benz CLS550, 2007–2018 Mercedes-Benz SL550, 2016–2017 Mercedes-Benz CLS400, 2017 Mercedes-Benz SL450, 2016 Mercedes-Benz SL400.