275/50R18
275/50R18 is uncommon as OEM fitment but appears as an aftermarket upsize option. At 28.83″ diameter with a 5.41″ sidewall (50% of section width), this size turns 700 revolutions per mile.
About 275/50R18
275/50R18 is less common as a factory fitment but is available as an aftermarket size, so SKU selection is narrower than mainstream OEM sizes. At 28.83″ overall diameter, 275/50R18 turns 700 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 265/50R18 drops diameter by 1.37%, which stays within the ±3% fitment safe zone for most vehicles. Stepping up to 255/55R18 adds 0.75% 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 28.83″ 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 aliases275/50R18
- Diameter
- 28.83″ / 732.2mm
- Section Width
- 10.83″
- Sidewall
- 5.41″ / 137.5mm
- Circumference
- 90.56″
- Revs/Mile
- 700
255/50R18
- Diameter
- 28.04″ / 712.2mm
- Section Width
- 10.04″
- Sidewall
- 5.02″ / 127.5mm
- Circumference
- 88.09″
- Revs/Mile
- 719
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 58.36 mph (93.92 km/h). Your speedometer reads 2.73% high versus actual speed.