255/55R19
255/55R19 ships as an OEM size on the Audi Q7, Mercedes-Benz GLE, Porsche Cayenne. At 30.04″ diameter with a 5.52″ sidewall (55% of section width), this size turns 671 revolutions per mile.
About 255/55R19
Factory fitments for 255/55R19 include the Audi Q7, Mercedes-Benz GLE, Porsche Cayenne — meaning replacement tires in this size see steady demand and broad brand availability. At 30.04″ overall diameter, 255/55R19 turns 671 revolutions per mile, which is the reference point the factory speedometer and odometer were calibrated against. The 55% aspect ratio gives it a moderate sidewall suited to sporty street driving and responsive turn-in. The 19″ 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 245/55R19 drops diameter by 1.44%, which stays within the ±3% fitment safe zone for most vehicles. Stepping up to 235/60R19 adds 0.20% 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 aliases255/55R19
- Diameter
- 30.04″ / 763.1mm
- Section Width
- 10.04″
- Sidewall
- 5.52″ / 140.25mm
- Circumference
- 94.38″
- Revs/Mile
- 671
235/55R19
- Diameter
- 29.18″ / 741.1mm
- Section Width
- 9.25″
- Sidewall
- 5.09″ / 129.25mm
- Circumference
- 91.66″
- Revs/Mile
- 691
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 58.27 mph (93.78 km/h). Your speedometer reads 2.88% high versus actual speed.