225/40R18 vs 225/45R17

225/45R17 is 3.0 mm shorter than 225/40R18 in overall diameter (−0.5%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 225/45R17 fitted, the speedometer reads 100 km/h when you are doing 99.5 km/h.

Dimensions side by side

	225/40R18	225/45R17
Overall diameter	637 mm (25.1″)	634 mm (25.0″)
Section width	225 mm	225 mm
Sidewall height	90 mm	101 mm
Rim	18″	17″
Revolutions per km	500	502
In stock	77 tires from $110.00	59 tires from $101.00

What changes

Overall diameter: 225/45R17 is 3.0 mm shorter (−0.5%).
Speedometer: reads 100 km/h at an actual 99.5 km/h with 225/45R17.
Wheel size changes from 18″ to 17″: 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 225/40R18

Vehicles that use 225/45R17

See every alternate size for 225/40R18

Frequently asked questions

Can I use 225/45R17 instead of 225/40R18?

Usually, yes: 225/45R17 is within 3% of the overall diameter of 225/40R18 (−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 225/40R18 and 225/45R17?

With 225/45R17 instead of 225/40R18, the speedometer shows 100 km/h when you are actually doing 99.5 km/h.

Which vehicles came with both 225/40R18 and 225/45R17?

Both sizes were original equipment, on different trims or packages, on the 2006–2019, 2022–2024 Audi A3, 2016–2024 Mini Clubman, 2016–2024 Mini Cooper, 2020–2024 BMW 228i, 2016–2020 Lexus IS, 2017–2020 Mercedes-Benz SLC300.