265/60R18 vs 265/65R17

Switching from 265/60R18 to 265/65R17 increases the overall diameter by 1.1 mm (0.1%). That is within the usual ±3% guideline.

265/60R18265/65R17Difference (mm / revs)
Section width265 mm265 mm+0.0
Sidewall height159.0 mm172.2 mm+13.2
Rim diameter457.2 mm431.8 mm-25.4
Overall diameter775.2 mm776.3 mm+1.1
Circumference2,435.4 mm2,438.8 mm+3.4
Revolutions411 per km410 per km-1.0

Speedometer effect

With 265/65R17 fitted on a car calibrated for 265/60R18, the real speed when the speedometer shows:

Speedometer showsActual speed
50 km/h50.1 km/h
80 km/h80.1 km/h
100 km/h100.1 km/h
120 km/h120.2 km/h

Larger tires make the car go faster than the speedometer shows. Most speedometers also read slightly high from the factory.

Before you change size

265/60R18 dimensions · 265/65R17 dimensions · Open in calculator