215/50R18
215/50R18 ships as an OEM size on the Mazda CX-3. At 26.46″ diameter with a 4.23″ sidewall (50% of section width), this size turns 762 revolutions per mile.
About 215/50R18
Factory fitments for 215/50R18 include the Mazda CX-3 — meaning replacement tires in this size see steady demand and broad brand availability. At 26.46″ overall diameter, 215/50R18 turns 762 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 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 235/45R18 drops diameter by 0.52%, which stays within the ±3% fitment safe zone for most vehicles. Stepping up to 225/50R18 adds 1.49% 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 26.46″ 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 aliases215/50R18
- Diameter
- 26.46″ / 672.2mm
- Section Width
- 8.46″
- Sidewall
- 4.23″ / 107.5mm
- Circumference
- 83.14″
- Revs/Mile
- 762
215/45R18
- Diameter
- 25.62″ / 650.7mm
- Section Width
- 8.46″
- Sidewall
- 3.81″ / 96.75mm
- Circumference
- 80.48″
- Revs/Mile
- 787
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 58.08 mph (93.47 km/h). Your speedometer reads 3.20% high versus actual speed.