How tall is a 255/45R20 tire?

A 255/45R20 has a nominal overall diameter of 29.04 inches (738 mm), calculated as the 20-inch wheel plus two sidewalls. This is the unloaded figure — a fitted tire sits fractionally shorter under the weight of the vehicle.

What wheel size does a 255/45R20 tire fit?

A 255/45R20 fits a wheel of 20 inches in diameter. The wheel also has to be within the rim width range the manufacturer publishes for this size, which is printed in the tire's spec sheet.

What do the numbers in 255/45R20 mean?

255 is the section width in millimetres. 45 is the aspect ratio — the sidewall is 45% of the width, so 114.8 mm here. R marks the construction (radial). 20 is the wheel diameter in inches.

Size Dimensions & Specs

Tires Size 255/45R20

Dimensions, specs, and every size 255/45R20 tire currently in stock

Overall Height

29.04"

738 mm · calculated

Section Width

255 mm

10.04 inches

Sidewall Height

4.52"

114.8 mm · 45% profile

Wheel Diameter

20"

508.0 mm

255/45R20 Specifications

Read directly from the size code. Load index, speed rating, and rim width range vary by model.

Specification	Imperial	Metric
Section width	10.04 in	255 mm
Aspect ratio	45%	—
Sidewall height	4.52 in	114.8 mm
Overall diameter (calculated)	29.04 in	738 mm
Wheel / rim diameter	20 in	508.0 mm
Construction	Radial	—

What does 255/45R20 mean?

Reading the code on your sidewall

Section width

255 mm

The distance from sidewall to sidewall across the tire's widest point.

Aspect ratio

45% profile

The sidewall stands 45% of the section width, which is 114.8 mm on this size.

Construction (R)

Radial

The body plies run across the tire at right angles to the direction of travel.

Wheel diameter

20 in

Fits a wheel measuring 20 inches across.

255/45R20 Questions & Answers

Dimensions and fitment guidelines for size 255/45R20

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