255/40R21 in Inches

A 255/40R21 tire has a 29-inch diameter, a 10-inch width, and is designed for a 21-inch rim.

In high flotation terms, this tire is labeled as 29x10R21.

255/40R21 Tire Size
255/40R21 Tire Size in Inches
255/40R21 Tire Circumference
694.7 revs/mile

255/40R21 Tire Overview

29 inches
Wheel Diameter
21 inches
Tire Width
10 inches
91.2 inches
Sidewall Height
4 inches
694.7 per mile

What does 255/40R21 mean?

255/40R21 tire size meaning in inches

255/40R21 is a tire size with the following dimensions:

  • 255 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.
  • 21 is the diameter of the wheel in inches, on which the tire is to be mounted.

255/40R21 Tire Conversion

Tire Diameter29 in737.4 mm
Section Width10 in255 mm
Rim Height21 in533 mm
Sidewall Height4 in102 mm
Circumference91.2 in2316.6 mm
Revolutions694.7 revs/mile
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FAQ About 255/40R21 Tire

How tall is a 255/40R21 tire?

The height (or diameter) of a 255/40R21 tire is 29 inches

How wide is a 255/40R21 tire?

The width of a 255/40R21 tire is 255 mm, which is about 10 inches.

What size rim fits a 255/40R21 tire?

A 255/40R21 tire fits on a rim that is 21 inches in diameter.

What does the 40 in a 255/40R21 tire mean?

The 40 in a 255/40R21 tire refers to the aspect ratio, meaning the height of the tire's sidewall is 40% of its width.

Alternative Tire Sizes for 255/40R21

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 255/40R21:

Tire SizeDiameterRim
235/45R2129.3″ (1.0%)21 x 7.5-9.0
245/40R2128.7″ (-1.0%)21 x 8.0-9.5
245/45R2129.7″ (2.4%)21 x 7.5-9.0
265/35R2128.3″ (-2.4%)21 x 9.0-10.5
265/40R2129.3″ (1.0%)21 x 9.0-10.5
275/35R2128.6″ (-1.4%)21 x 9.0-11.0
275/40R2129.7″ (2.4%)21 x 9.0-11.0
285/35R2128.9″ (-0.3%)21 x 9.5-11.0
295/35R2129.1″ (0.3%)21 x 10.0-11.5
305/30R2128.2″ (-2.8%)21 x 10.5-11.5
305/35R2129.4″ (1.4%)21 x 10.0-12.0
315/30R2128.4″ (-2.1%)21 x 10.5-11.5
315/35R2129.7″ (2.4%)21 x 10.5-12.5
325/30R2128.7″ (-1.0%)21 x 11.0-12.0