255/50R20
255/50R20 ships as an OEM size on the Acura MDX, Ford Edge, Honda Pilot. At 30.04″ diameter with a 5.02″ sidewall (50% of section width), this size turns 671 revolutions per mile.
About 255/50R20
Factory fitments for 255/50R20 include the Acura MDX, Ford Edge, Honda Pilot, INFINITI QX60 — meaning replacement tires in this size see steady demand and broad brand availability. At 30.04″ overall diameter, 255/50R20 turns 671 revolutions per mile, which is the reference point the factory speedometer and odometer were calibrated against. The 50% 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 245/50R20 drops diameter by 1.31%, which stays within the ±3% fitment safe zone for most vehicles. Stepping up to 235/55R20 adds 0.46% 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 30.04″ 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 aliases255/50R20
- Diameter
- 30.04″ / 763mm
- Section Width
- 10.04″
- Sidewall
- 5.02″ / 127.5mm
- Circumference
- 94.37″
- Revs/Mile
- 671
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 58.43 mph (94.03 km/h). Your speedometer reads 2.62% high versus actual speed.