245/65R18
245/65R18 is uncommon as OEM fitment but appears as an aftermarket upsize option. At 30.54″ diameter with a 6.27″ sidewall (65% of section width), this size turns 660 revolutions per mile.
About 245/65R18
245/65R18 is less common as a factory fitment but is available as an aftermarket size, so SKU selection is narrower than mainstream OEM sizes. At 30.54″ overall diameter, 245/65R18 turns 660 revolutions per mile, which is the reference point the factory speedometer and odometer were calibrated against. The 65% aspect ratio gives it a balanced sidewall — enough compliance for daily comfort without vague steering. The 18″ rim pairing is typical for full-size truck, premium SUV, and sport-sedan platforms, so compatible wheels are easy to source new or used. Going one step shorter to 255/60R18 drops diameter by 1.61%, which stays within the ±3% fitment safe zone for most vehicles. Stepping up to 255/65R18 adds 1.68% 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 30.54″ 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 aliases245/65R18
- Diameter
- 30.54″ / 775.7mm
- Section Width
- 9.65″
- Sidewall
- 6.27″ / 159.25mm
- Circumference
- 95.94″
- Revs/Mile
- 660
225/65R18
- Diameter
- 29.52″ / 749.7mm
- Section Width
- 8.86″
- Sidewall
- 5.76″ / 146.25mm
- Circumference
- 92.73″
- Revs/Mile
- 683
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 57.99 mph (93.32 km/h). Your speedometer reads 3.35% high versus actual speed.