My Tire Guide

305/45R20 tire size

A 305/45R20 tire stands 30.8 inches tall and 12.0 inches wide, with a 5.4-inch sidewall on a 20-inch rim.

30.8″OVERALL 30.8 IN · RIM 20 IN12.0″5.4″WIDTH · SIDEWALL
Overall height
30.8 in783 mm
Section width
12.0 in305 mm
Sidewall height
5.4 in137 mm
Rim diameter
20 in508 mm
Circumference
96.8 in2458 mm
Revolutions per mile
655407 per km
Inch size
30.8x12.0R20

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

Sizes you can swap to

These 20-inch sizes are within two width steps and 3% of a 305/45R20's overall height, the usual limit before the speedometer, ABS and transmission notice. The closest is 295/45R20, 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
295/45R20−1.2%−0.35 in−10 mm59.3 mph
315/45R20+1.2%+0.35 in+10 mm60.7 mph
285/50R20+1.3%+0.41 in−20 mm60.8 mph
285/45R20−2.3%−0.71 in−20 mm58.6 mph
295/50R20+2.6%+0.81 in−10 mm61.6 mph
315/40R20−2.9%−0.89 in+10 mm58.3 mph

Plus and minus sizes

Changing rim size means changing the sidewall to keep the same overall height. On 18-inch or 19-inch or 21-inch or 22-inch rims, these are the closest matches to a 305/45R20.

SizeHeightWidthAt 60 mph
295/55R18−0.1%−0.03 in−10 mm59.9 mph
275/55R19+0.3%+0.10 in−30 mm60.2 mph
275/45R21−0.2%−0.06 in−30 mm59.9 mph
315/35R22−0.4%−0.13 in+10 mm59.8 mph

Other 20-inch sizes near 305/45R20

305 mm wide, other sidewalls

45 series, other widths

See the other sizes for this rim on 20-inch tire sizes, or other tires about this tall on 31-inch tires.

Shop 305/45R20 tires

These open each store's own list of 305/45R20 tires, where you can filter by type, load and speed rating.

305/45R20 questions

How tall is a 305/45R20 tire?

About 30.8 inches (783 mm) from the ground to the top of the tread, unloaded. On the vehicle, carrying weight, it sits a little lower.

What does 305/45R20 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 20 is the rim diameter in inches.

Can I use 295/45R20 instead of 305/45R20?

295/45R20 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 305/45R20 in inches?

In inch terms it is 30.8x12.0R20: 30.8 inches tall, 12.0 inches wide, for a 20-inch rim.

How many revolutions per mile does a 305/45R20 make?

About 655 turns per mile, worked out from its unloaded circumference of 96.8 inches. Makers list slightly higher numbers for their own tires, because a loaded tire rolls on a smaller radius.