275/30R20
275/30R20 is uncommon as OEM fitment but appears as an aftermarket upsize option. At 26.50″ diameter with a 3.25″ sidewall (30% of section width), this size turns 761 revolutions per mile.
About 275/30R20
275/30R20 is less common as a factory fitment but is available as an aftermarket size, so SKU selection is narrower than mainstream OEM sizes. At 26.50″ overall diameter, 275/30R20 turns 761 revolutions per mile, which is the reference point the factory speedometer and odometer were calibrated against. The 30% aspect ratio gives it an ultra-low-profile sidewall tuned for maximum steering precision — at the cost of ride comfort and rim protection. The 20″ rim pairing is typical for luxury SUV and performance-oriented platforms, so compatible wheels are easy to source new or used. Stepping up to 285/30R20 adds 0.89% 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 26.50″ 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 aliases275/30R20
- Diameter
- 26.5″ / 673mm
- Section Width
- 10.83″
- Sidewall
- 3.25″ / 82.5mm
- Circumference
- 83.24″
- Revs/Mile
- 761
255/35R20
- Diameter
- 27.03″ / 686.5mm
- Section Width
- 10.04″
- Sidewall
- 3.51″ / 89.25mm
- Circumference
- 84.91″
- Revs/Mile
- 746
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 61.2 mph (98.5 km/h). Your speedometer reads 2.01% low versus actual speed.