235/35R19 vs 235/40R18

235/40R18 is 2.0 mm shorter than 235/35R19 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

	235/35R19	235/40R18
Overall diameter	647 mm (25.5″)	645 mm (25.4″)
Section width	235 mm	235 mm
Sidewall height	82 mm	94 mm
Rim	19″	18″
Revolutions per km	492	494
In stock	31 tires from $111.00	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.
Wheel size changes from 19″ 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 235/35R19

Vehicles that use 235/40R18

See every alternate size for 235/35R19

Frequently asked questions

Can I use 235/40R18 instead of 235/35R19?

Usually, yes: 235/40R18 is within 3% of the overall diameter of 235/35R19 (−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 235/35R19 and 235/40R18?

With 235/40R18 instead of 235/35R19, the speedometer shows 100 km/h when you are actually doing 99.7 km/h.

Which vehicles came with both 235/35R19 and 235/40R18?

Both sizes were original equipment, on different trims or packages, on the 2020–2024 Cadillac CT4, 2020–2024 Mercedes-Benz CLA35, 2015–2021 Alfa Romeo 4C, 2019–2021 Honda Civic, 2020–2021 Mercedes-Benz A35 AMG, 2014–2019 Mercedes-Benz CLA45.