How tall is a 315/30R18 tire?

A 315/30R18 has a nominal overall diameter of 25.44 inches (646 mm), calculated as the 18-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 315/30R18 tire fit?

A 315/30R18 fits a wheel of 18 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 315/30R18 mean?

315 is the section width in millimetres. 30 is the aspect ratio — the sidewall is 30% of the width, so 94.5 mm here. R marks the construction (radial). 18 is the wheel diameter in inches.

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Size Dimensions & Specs

Tires Size 315/30R18

Dimensions, specs, and every size 315/30R18 tire currently in stock

Overall Height

25.44"

646 mm · calculated

Section Width

315 mm

12.4 inches

Sidewall Height

3.72"

94.5 mm · 30% profile

Wheel Diameter

18"

457.2 mm

315/30R18 Specifications

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

Specification	Imperial	Metric
Section width	12.4 in	315 mm
Aspect ratio	30%	—
Sidewall height	3.72 in	94.5 mm
Overall diameter (calculated)	25.44 in	646 mm
Wheel / rim diameter	18 in	457.2 mm
Construction	Radial	—

What does 315/30R18 mean?

Reading the code on your sidewall

Section width

315 mm

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

Aspect ratio

30% profile

The sidewall stands 30% of the section width, which is 94.5 mm on this size.

Construction (R)

Radial

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

Wheel diameter

18 in

Fits a wheel measuring 18 inches across.

315/30R18 Questions & Answers

Dimensions and fitment guidelines for size 315/30R18

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Tires Size 315/30R18

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315/30R18 Specifications

What does 315/30R18 mean?

315 mm

30% profile

Radial

18 in

315/30R18 Questions & Answers

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