My Tire Guide

305/45R18 tire size

A 305/45R18 tire stands 28.8 inches tall and 12.0 inches wide, with a 5.4-inch sidewall on an 18-inch rim.

28.8″OVERALL 28.8 IN · RIM 18 IN12.0″5.4″WIDTH · SIDEWALL
Overall height
28.8 in732 mm
Section width
12.0 in305 mm
Sidewall height
5.4 in137 mm
Rim diameter
18 in457 mm
Circumference
90.5 in2299 mm
Revolutions per mile
700435 per km
Inch size
28.8x12.0R18

Compare it with any other size in the tire size calculator.

Sizes you can swap to

These 18-inch sizes are within two width steps and 3% of a 305/45R18's overall height, the usual limit before the speedometer, ABS and transmission notice. The closest is 295/45R18, 1.2% shorter (0.35 in). Wider sizes also need room in the wheel well and a rim width that suits them.

SizeHeightWidthAt 60 mph
295/45R18−1.2%−0.35 in−10 mm59.3 mph
315/45R18+1.2%+0.35 in+10 mm60.7 mph
285/50R18+1.4%+0.41 in−20 mm60.9 mph
285/45R18−2.5%−0.71 in−20 mm58.5 mph
295/50R18+2.8%+0.81 in−10 mm61.7 mph

Plus and minus sizes

Changing rim size means changing the sidewall to keep the same overall height. On 16-inch or 17-inch or 19-inch or 20-inch rims, these are the closest matches to a 305/45R18.

SizeHeightWidthAt 60 mph
295/55R16−0.1%−0.03 in−10 mm59.9 mph
275/55R17+0.4%+0.10 in−30 mm60.2 mph
275/45R19−0.2%−0.06 in−30 mm59.9 mph
315/35R20−0.4%−0.13 in+10 mm59.7 mph

Other 18-inch sizes near 305/45R18

305 mm wide, other sidewalls

45 series, other widths

See the other sizes for this rim on 18-inch tire sizes.

Shop 305/45R18 tires

These open each store's own list of 305/45R18 tires, where you can filter by type, load and speed rating.

305/45R18 questions

How tall is a 305/45R18 tire?

About 28.8 inches (732 mm) from the ground to the top of the tread, unloaded. On the vehicle, carrying weight, it sits a little lower.

What does 305/45R18 mean?

305 is the section width in millimetres (12.0 in). 45 means the sidewall is 45% of that width: 137 mm, or 5.4 in. R means radial construction, and 18 is the rim diameter in inches.

Can I use 295/45R18 instead of 305/45R18?

295/45R18 is 1.2% shorter (0.35 in) and 10 mm narrower, which is inside the usual 3% rule. With it fitted, the speedometer shows 60 mph when you are doing 59.3 mph.

What is 305/45R18 in inches?

In inch terms it is 28.8x12.0R18: 28.8 inches tall, 12.0 inches wide, for an 18-inch rim.

How many revolutions per mile does a 305/45R18 make?

About 700 turns per mile, worked out from its unloaded circumference of 90.5 inches. Makers list slightly higher numbers for their own tires, because a loaded tire rolls on a smaller radius.