225/40R19 vs 225/45R18
225/45R18 is 3.0 mm shorter than 225/40R19 in overall diameter (−0.5%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 225/45R18 fitted, the speedometer reads 100 km/h when you are doing 99.5 km/h.
Dimensions side by side
| 225/40R19 | 225/45R18 | |
|---|---|---|
| Overall diameter | 663 mm (26.1″) | 660 mm (26.0″) |
| Section width | 225 mm | 225 mm |
| Sidewall height | 90 mm | 101 mm |
| Rim | 19″ | 18″ |
| Revolutions per km | 480 | 482 |
| In stock | 37 tires from $116.00 | 95 tires from $112.00 |
What changes
- Overall diameter: 225/45R18 is 3.0 mm shorter (−0.5%).
- Speedometer: reads 100 km/h at an actual 99.5 km/h with 225/45R18.
- 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 225/40R19
Vehicles that use 225/45R18
See every alternate size for 225/40R19
Frequently asked questions
Can I use 225/45R18 instead of 225/40R19?
Usually, yes: 225/45R18 is within 3% of the overall diameter of 225/40R19 (−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 225/40R19 and 225/45R18?
With 225/45R18 instead of 225/40R19, the speedometer shows 100 km/h when you are actually doing 99.5 km/h.
Which vehicles came with both 225/40R19 and 225/45R18?
Both sizes were original equipment, on different trims or packages, on the 2017–2024 BMW 430i, 2015–2024 Mercedes-Benz C300, 2019–2024 BMW 330i, 2021–2024 BMW M440i, 2017–2024 Alfa Romeo Giulia, 2020–2024 Mercedes-Benz CLA250.