185/70R15
185/70R15 is uncommon as OEM fitment but appears as an aftermarket upsize option. At 25.20″ diameter with a 5.10″ sidewall (70% of section width), this size turns 800 revolutions per mile.
About 185/70R15
185/70R15 is less common as a factory fitment but is available as an aftermarket size, so SKU selection is narrower than mainstream OEM sizes. At 25.20″ overall diameter, 185/70R15 turns 800 revolutions per mile, which is the reference point the factory speedometer and odometer were calibrated against. The 70% aspect ratio gives it a tall, compliant sidewall that absorbs bumps well and protects rims off-road. The 15″ rim pairing is typical for compact-car and economy-vehicle platforms, so compatible wheels are easy to source new or used. Going one step shorter to 195/65R15 drops diameter by 0.86%, which stays within the ±3% fitment safe zone for most vehicles. Stepping up to 205/65R15 adds 1.17% 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 25.20″ 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 aliases185/70R15
- Diameter
- 25.2″ / 640mm
- Section Width
- 7.28″
- Sidewall
- 5.1″ / 129.5mm
- Circumference
- 79.16″
- Revs/Mile
- 800
175/65R15
- Diameter
- 23.96″ / 608.5mm
- Section Width
- 6.89″
- Sidewall
- 4.48″ / 113.75mm
- Circumference
- 75.26″
- Revs/Mile
- 842
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 57.05 mph (91.81 km/h). Your speedometer reads 4.92% high versus actual speed.