255/45R20 tire size

A 255/45R20 tire is 255 mm wide with a sidewall 45% of its width (114.8 mm), fits a 20-inch rim and has an overall diameter of 738 mm (29.0 in).

DimensionMetricImperial
Section width255 mm10.04 in
Sidewall height114.8 mm4.52 in
Rim diameter508.0 mm20 in
Overall diameter737.5 mm29.04 in
Circumference2,316.9 mm91.22 in
Revolutions432 per km695 per mile

Reading the size 255/45R20

255Width in mm45Aspect ratio (sidewall % of width)RRadial construction20Rim diameter in inches

The load index and speed rating (for example 91V) follow the size on the sidewall. Replacement tires should match or exceed the original load index and speed rating.

Alternative sizes within 3% of 255/45R20

A replacement size should stay within about 3% of the original diameter so the speedometer, ABS and transmission stay accurate. Always check clearance, load index and the vehicle manufacturer's approved sizes.

SizeDiameterDifferenceSpeedo reads 100 → actual
255/50R19738 mm+0.0%100.0Compare
235/65R17737 mm-0.0%100.0Compare
255/55R18738 mm+0.0%100.0Compare
235/60R18739 mm+0.2%100.2Compare
235/70R16735 mm-0.3%99.7Compare
235/55R19741 mm+0.5%100.5Compare
235/75R15734 mm-0.5%99.5Compare
225/55R19730 mm-1.0%99.0

Compare 255/45R20 with any size →

Other 20-inch sizes