265/40R20
265/40R20 is uncommon as OEM fitment but appears as an aftermarket upsize option. At 28.35″ diameter with a 4.17″ sidewall (40% of section width), this size turns 711 revolutions per mile.
About 265/40R20
265/40R20 is less common as a factory fitment but is available as an aftermarket size, so SKU selection is narrower than mainstream OEM sizes. At 28.35″ overall diameter, 265/40R20 turns 711 revolutions per mile, which is the reference point the factory speedometer and odometer were calibrated against. The 40% 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 1.11%, which stays within the ±3% fitment safe zone for most vehicles. Stepping up to 275/40R20 adds 1.11% 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 28.35″ 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 aliases265/40R20
- Diameter
- 28.35″ / 720mm
- Section Width
- 10.43″
- Sidewall
- 4.17″ / 106mm
- Circumference
- 89.05″
- Revs/Mile
- 711
245/40R20
- Diameter
- 27.72″ / 704mm
- Section Width
- 9.65″
- Sidewall
- 3.86″ / 98mm
- Circumference
- 87.07″
- Revs/Mile
- 728
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 58.67 mph (94.41 km/h). Your speedometer reads 2.22% high versus actual speed.