235/55R18
235/55R18 ships as an OEM size on the Chrysler 300, Dodge Challenger, Volkswagen Tiguan. At 28.18″ diameter with a 5.09″ sidewall (55% of section width), this size turns 716 revolutions per mile.
About 235/55R18
Factory fitments for 235/55R18 include the Chrysler 300, Dodge Challenger, Volkswagen Tiguan — meaning replacement tires in this size see steady demand and broad brand availability. At 28.18″ overall diameter, 235/55R18 turns 716 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 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 215/60R18 drops diameter by 0.07%, which stays within the ±3% fitment safe zone for most vehicles. Stepping up to 225/60R18 adds 1.61% 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 28.18″ 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 aliases235/55R18
- Diameter
- 28.18″ / 715.7mm
- Section Width
- 9.25″
- Sidewall
- 5.09″ / 129.25mm
- Circumference
- 88.52″
- Revs/Mile
- 716
215/55R18
- Diameter
- 27.31″ / 693.7mm
- Section Width
- 8.46″
- Sidewall
- 4.66″ / 118.25mm
- Circumference
- 85.8″
- Revs/Mile
- 738
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 58.16 mph (93.59 km/h). Your speedometer reads 3.07% high versus actual speed.