235/45R18 tire size

A 235/45R18 tire is 235 mm wide with a sidewall 45% of its width (105.8 mm), fits a 18-inch rim and has an overall diameter of 669 mm (26.3 in).

DimensionMetricImperial
Section width235 mm9.25 in
Sidewall height105.8 mm4.16 in
Rim diameter457.2 mm18 in
Overall diameter668.7 mm26.33 in
Circumference2,100.8 mm82.71 in
Revolutions476 per km766 per mile

Reading the size 235/45R18

235Width in mm45Aspect ratio (sidewall % of width)RRadial construction18Rim 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 235/45R18

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
215/55R17668 mm-0.1%99.9Compare
235/40R19671 mm+0.3%100.3Compare
205/65R16673 mm+0.6%100.6Compare
215/60R16664 mm-0.6%99.4Compare
225/40R19663 mm-0.9%99.1Compare
255/35R19661 mm-1.1%98.9Compare
225/60R16676 mm+1.2%101.2
225/45R18660 mm-1.3%98.7

Compare 235/45R18 with any size →

Other 18-inch sizes

215/45R18215/55R18225/40R18225/45R18225/50R18225/55R18225/60R18235/40R18235/50R18235/55R18235/60R18235/65R18245/40R18245/45R18245/60R18255/55R18255/60R18255/65R18255/70R18265/35R18265/60R18265/65R18265/70R18275/65R18275/70R18