235/55R18 vs 245/45R20
245/45R20 is 13.0 mm taller than 235/55R18 in overall diameter (+1.8%), within the usual 3% limit, so it can replace it where the wheels and clearance allow. With 245/45R20 fitted, the speedometer reads 100 km/h when you are doing 101.8 km/h.
Dimensions side by side
| 235/55R18 | 245/45R20 | |
|---|---|---|
| Overall diameter | 716 mm (28.2″) | 729 mm (28.7″) |
| Section width | 235 mm | 245 mm |
| Sidewall height | 129 mm | 110 mm |
| Rim | 18″ | 20″ |
| Revolutions per km | 445 | 437 |
| In stock | 60 tires from $128.00 | 52 tires from $167.00 |
What changes
- Overall diameter: 245/45R20 is 13.0 mm taller (+1.8%).
- Speedometer: reads 100 km/h at an actual 101.8 km/h with 245/45R20.
- 245/45R20 is 10 mm wider, so check clearance and the recommended rim width.
- Wheel size changes from 18″ to 20″: 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 235/55R18
Vehicles that use 245/45R20
See every alternate size for 235/55R18
Frequently asked questions
Can I use 245/45R20 instead of 235/55R18?
Usually, yes: 245/45R20 is within 3% of the overall diameter of 235/55R18 (+1.8%). 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 235/55R18 and 245/45R20?
With 245/45R20 instead of 235/55R18, the speedometer shows 100 km/h when you are actually doing 101.8 km/h.
Which vehicles came with both 235/55R18 and 245/45R20?
Both sizes were original equipment, on different trims or packages, on the 2019–2023 Volvo XC40, 2009–2022 Dodge Challenger, 2015–2019 Ford Taurus, 2018–2019 Volvo V90 Cross Country, 2011–2018 Dodge Charger, 2011–2012 Lincoln MKS.