315/40R18 in Inches

A 315/40R18 tire has a 27.9-inch diameter, a 12.4-inch width, and is designed for a 18-inch rim.

In high flotation terms, this tire is labeled as 27.9x12.4R18.

315/40R18 Tire Size
12.4"
27.9"
315/40R18 Tire Size in Inches
315/40R18 Tire Circumference
87.7"
18"
5"
722.3 revs/mile

315/40R18 Tire Overview

Height
27.9 inches
Wheel Diameter
18 inches
Tire Width
12.4 inches
Circumference
87.7 inches
Sidewall Height
5 inches
Revolutions
722.3 per mile
Tirelib.com

What does 315/40R18 mean?

315/40R18 tire size meaning in inches

315/40R18 is a tire size with the following dimensions:

  • 315 is the width of the tire in millimeters. This number also indicates the appropriate width of the rim on which the tire should be mounted.
  • 40 is the aspect ratio, which is the ratio of the tire's height to its width. This affects the tire's handling and ride comfort
  • R indicates the tire's construction type, meaning it has a radial construction. This provides stability and precision to the tire.
  • 18 is the diameter of the wheel in inches, on which the tire is to be mounted.

315/40R18 Tire Conversion

DimensionsInchesMillimeters
Tire Diameter27.9 in709.2 mm
Section Width12.4 in315 mm
Rim Height18 in457 mm
Sidewall Height5 in126 mm
Circumference87.7 in2228 mm
Revolutions722.3 revs/mile
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FAQ About 315/40R18 Tire

How tall is a 315/40R18 tire?

The height (or diameter) of a 315/40R18 tire is 27.9 inches

How wide is a 315/40R18 tire?

The width of a 315/40R18 tire is 315 mm, which is about 12.4 inches.

What size rim fits a 315/40R18 tire?

A 315/40R18 tire fits on a rim that is 18 inches in diameter.

What does the 40 in a 315/40R18 tire mean?

The 40 in a 315/40R18 tire refers to the aspect ratio, meaning the height of the tire's sidewall is 40% of its width.

Alternative Tire Sizes for 315/40R18

Typically, it's recommended to choose a tire with a diameter (height) within 3% of the original equipment manufacturer (OEM) tire size.

However, keep in mind that this is a general guideline and not an absolute rule.

Here are some tire sizes that are compatible with the 315/40R18:

Tire SizeDiameterRim
145/80R1827.1″ (-2.9%)18 x n/a
145/85R1827.7″ (-0.7%)18 x n/a
155/80R1827.8″ (-0.4%)18 x n/a
155/85R1828.4″ (1.8%)18 x n/a
165/70R1827.1″ (-2.9%)18 x n/a
205/60R1827.7″ (-0.7%)18 x 5.0-7.5
215/55R1827.3″ (-2.2%)18 x 6.0-7.5
225/55R1827.7″ (-0.7%)18 x 6.0-8.0
225/60R1828.6″ (2.5%)18 x 6.0-8.0
235/50R1827.3″ (-2.2%)18 x 6.5-8.5
235/55R1828.2″ (1.1%)18 x 6.5-8.5
245/50R1827.6″ (-1.1%)18 x 7.0-8.5
245/55R1828.6″ (2.5%)18 x 7.0-8.5
255/50R1828.0″ (0.4%)18 x 7.0-9.0
265/45R1827.4″ (-1.8%)18 x 8.5-10.0
265/50R1828.4″ (1.8%)18 x 7.5-9.5
275/45R1827.7″ (-0.7%)18 x 8.5-10.5
285/45R1828.1″ (0.7%)18 x 9.0-10.5
295/40R1827.3″ (-2.2%)18 x 10.0-11.5
295/45R1828.5″ (2.2%)18 x 9.5-11.0
305/40R1827.6″ (-1.1%)18 x 10.0-12.0
335/35R1827.2″ (-2.5%)18 x n/a
345/35R1827.5″ (-1.4%)18 x 11.5-13.5