225/50R18
225/50R18 ships as an OEM size on the Subaru Legacy. At 26.86″ diameter with a 4.43″ sidewall (50% of section width), this size turns 751 revolutions per mile.
About 225/50R18
Factory fitments for 225/50R18 include the Subaru Legacy — meaning replacement tires in this size see steady demand and broad brand availability. At 26.86″ overall diameter, 225/50R18 turns 751 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 215/50R18 drops diameter by 1.47%, which stays within the ±3% fitment safe zone for most vehicles. Stepping up to 235/50R18 adds 1.47% 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 26.86″ 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 aliases225/50R18
- Diameter
- 26.86″ / 682.2mm
- Section Width
- 8.86″
- Sidewall
- 4.43″ / 112.5mm
- Circumference
- 84.38″
- Revs/Mile
- 751
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 57.23 mph (92.1 km/h). Your speedometer reads 4.62% high versus actual speed.