245/55R20
245/55R20 is uncommon as OEM fitment but appears as an aftermarket upsize option. At 30.61″ diameter with a 5.31″ sidewall (55% of section width), this size turns 659 revolutions per mile.
About 245/55R20
245/55R20 is less common as a factory fitment but is available as an aftermarket size, so SKU selection is narrower than mainstream OEM sizes. At 30.61″ overall diameter, 245/55R20 turns 659 revolutions per mile, which is the reference point the factory speedometer and odometer were calibrated against. The 55% aspect ratio gives it a moderate sidewall suited to sporty street driving and responsive turn-in. The 20″ rim pairing is typical for luxury SUV and performance-oriented platforms, so compatible wheels are easy to source new or used. Going one step shorter to 235/55R20 drops diameter by 1.41%, which stays within the ±3% fitment safe zone for most vehicles. Stepping up to 255/55R20 adds 1.41% diameter — also inside the safe window, with marginally taller ride height. If you are shopping for a direct replacement, any tire within roughly ±0.7″ of the 30.61″ stock diameter (about ±2% in percentage terms) will keep ABS, TPMS, and odometer readings inside the vehicle's designed tolerance.
Compare with another size
275/65R18 or "33" for inch aliases245/55R20
- Diameter
- 30.61″ / 777.5mm
- Section Width
- 9.65″
- Sidewall
- 5.31″ / 134.75mm
- Circumference
- 96.16″
- Revs/Mile
- 659
235/50R20
- Diameter
- 29.25″ / 743mm
- Section Width
- 9.25″
- Sidewall
- 4.63″ / 117.5mm
- Circumference
- 91.9″
- Revs/Mile
- 689
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 57.34 mph (92.28 km/h). Your speedometer reads 4.44% high versus actual speed.