225/40R18 vs 245/45R17
245/45R17 is 15.0 mm taller than 225/40R18 in overall diameter (+2.4%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 245/45R17 fitted, the speedometer reads 100 km/h when you are doing 102.4 km/h.
Dimensions side by side
| 225/40R18 | 245/45R17 | |
|---|---|---|
| Overall diameter | 637 mm (25.1″) | 652 mm (25.7″) |
| Section width | 225 mm | 245 mm |
| Sidewall height | 90 mm | 110 mm |
| Rim | 18″ | 17″ |
| Revolutions per km | 500 | 488 |
| In stock | 77 tires from $110.00 | 18 tires from $113.00 |
What changes
- Overall diameter: 245/45R17 is 15.0 mm taller (+2.4%).
- Speedometer: reads 100 km/h at an actual 102.4 km/h with 245/45R17.
- 245/45R17 is 20 mm wider, so check clearance and the recommended rim width.
- 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 245/45R17
See every alternate size for 225/40R18
Frequently asked questions
Can I use 245/45R17 instead of 225/40R18?
Usually, yes: 245/45R17 is within 3% of the overall diameter of 225/40R18 (+2.4%). 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 225/40R18 and 245/45R17?
With 245/45R17 instead of 225/40R18, the speedometer shows 100 km/h when you are actually doing 102.4 km/h.
Which vehicles came with both 225/40R18 and 245/45R17?
Both sizes were original equipment, on different trims or packages, on the 2010–2015 Lexus IS 250C, 2010–2015 Lexus IS 350C, 2006–2013 Lexus IS 250, 2006–2013 Lexus IS 350.