235/45R20
235/45R20 is uncommon as OEM fitment but appears as an aftermarket upsize option. At 28.33″ diameter with a 4.16″ sidewall (45% of section width), this size turns 712 revolutions per mile.
About 235/45R20
235/45R20 is less common as a factory fitment but is available as an aftermarket size, so SKU selection is narrower than mainstream OEM sizes. At 28.33″ overall diameter, 235/45R20 turns 712 revolutions per mile, which is the reference point the factory speedometer and odometer were calibrated against. The 45% aspect ratio gives it a low-profile sidewall that delivers sharp steering response but transmits road imperfections. 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 255/40R20 drops diameter by 1.04%, which stays within the ±3% fitment safe zone for most vehicles. Stepping up to 245/45R20 adds 1.25% 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 28.33″ 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 aliases235/45R20
- Diameter
- 28.33″ / 719.5mm
- Section Width
- 9.25″
- Sidewall
- 4.16″ / 105.75mm
- Circumference
- 88.99″
- Revs/Mile
- 712
235/40R20
- Diameter
- 27.4″ / 696mm
- Section Width
- 9.25″
- Sidewall
- 3.7″ / 94mm
- Circumference
- 86.08″
- Revs/Mile
- 736
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 58.04 mph (93.41 km/h). Your speedometer reads 3.27% high versus actual speed.