255/45R21 In Inches – Tire Size & Wheel Fitment Guide

What size tire is 255/45R21 in Inches?

The 255/45R21 tire has an overall diameter of 30 inches, a section width of 10 inches, and can be mounted on 21 x 9.5-11.0 inches rim. The equivalent tire size in the high flotation system is 30x10R21.

Tire Diameter30762.9
Section Width10255
Rim Height21533
Sidewall Height4.5114.8
tire diameter
Tire Side
Tire Circumference
671.5 Revs/Mile

To help you understand, we'll break down each part of the 255/45R21 tire size to know what these numbers represent & how they may affect your tire's performance:

How wide is a 255/45R21 tire?

The 255/45R21 tire has a width of 10 inches (255 mm). This is the measurement at its thickest point, the distance between the outer sidewall and the inner sidewall’s widest point, also called as tread width or section width.

tread width
Tread width: 10 In.

How tall is a 255/45R21 tire?

The 255/45R21 tire has a height of 30 inches (762.9 mm). This is the measurement from the bottom to the highest point at the top of a tire through its exact center when inflated and unloaded.

Tire Diameter
Tire diameter: 30 In.

255/45R21 sidewall height

The 255/45R21 has a sidewall height of 4.5 inches (114.8 mm). It’s measured from the rim to the outer edge of the tire's tread, expressed as a percentage of tire width.

sidewall height
Sidewall height: 4.5 In.

What size rim do you need for 255/45R21 tire?

You can mount the 255/45R21 tire on a rim with a height of 21 inches and a width ranging from 9.5-11.0 inches. (Based on recommendations of The Tire and Rim Association (TRA))

Putting very narrow tires on wide rims or vice versa can result in reduced performance of the tire.

Rim Diameter
Rim height: 21 In.
rim width
Rim width: 9.5-11.0 In.

255/45R21 circumference

The 255/45R21 tire has a circumference of 94.4 inches (2396.7 mm), This is the measurement of the distance the tire travels in one revolution.

The tire circumference is important for your vehicle's overall performance, affecting its speedometer acceleration, accuracy and fuel efficiency.

Circumference: 94.4 In.

255/45R21 Revolutions

The 255/45R21 performs 671.5 revs/mile. Revolutions per mile indicate the number of times a tire rotates while it covers the distance of one mile.

671.5 revs/mile

Replacement Tire Sizes for 255/45R21

As a rule, you can replace the tire within a 3% difference in tire diameter (height) of the OEM tire size. Here is a list of compatible tire sizes for 255/45R21:

Tire SizeDiameterRim (H x W)
315/40R2130.9″ (+2.9%)21″ x 10.5-12.5″
285/35R2330.9″ (+2.9%)23″ x 9.5-11.0″
275/50R2030.8″ (+2.6%)20″ x 7.5-9.5″
305/45R2030.8″ (+2.6%)20″ x 9.5-11.5″
275/45R2130.7″ (+2.3%)21″ x 8.5-10.5″
275/40R2230.7″ (+2.3%)22″ x 9.0-11.0″
315/35R2230.7″ (+2.3%)22″ x 10.5-12.5″
325/30R2330.7″ (+2.3%)23″ x n/a
285/30R2430.7″ (+2.3%)24″ x 9.5-10.5″
295/45R2030.5″ (+1.6%)20″ x 9.5-11.0″
275/30R2430.5″ (+1.6%)24″ x 9.0-10.0″
265/50R2030.4″ (+1.3%)20″ x 7.5-9.5″
265/45R2130.4″ (+1.3%)21″ x 8.5-10.0″
305/35R2230.4″ (+1.3%)22″ x 10.0-12.0″
295/40R2130.3″ (+1%)21″ x 10.0-11.5″
265/40R2230.3″ (+1%)22″ x 9.0-10.5″
235/55R2030.2″ (+0.7%)20″ x 6.5-8.5″
285/45R2030.1″ (+0.3%)20″ x 9.0-10.5″
295/35R2230.1″ (+0.3%)22″ x 10.0-11.5″
255/50R2030″ (Equal)20″ x 7.0-9.0″
285/40R2130″ (Equal)21″ x 9.5-11.0″
255/40R2230″ (Equal)22″ x 8.5-10.0″
295/30R2330″ (Equal)23″ x 10.0-11.0″
255/30R2430″ (Equal)24″ x 8.5-9.5″
285/35R2229.9″ (-0.3%)22″ x 9.5-11.0″
245/30R2429.8″ (-0.7%)24″ x n/a
275/45R2029.7″ (-1%)20″ x 8.5-10.5″
245/45R2129.7″ (-1%)21″ x 7.5-9.0″
275/40R2129.7″ (-1%)21″ x 9.0-11.0″
315/35R2129.7″ (-1%)21″ x 10.5-12.5″
245/50R2029.6″ (-1.4%)20″ x 7.0-8.5″
305/40R2029.6″ (-1.4%)20″ x 10.0-12.0″
275/35R2229.6″ (-1.4%)22″ x 9.0-11.0″
265/45R2029.4″ (-2%)20″ x 8.5-10.0″
305/35R2129.4″ (-2%)21″ x 10.0-12.0″
315/30R2229.4″ (-2%)22″ x 10.5-11.5″
275/25R2429.4″ (-2%)24″ x 9.5-10.0″
235/50R2029.3″ (-2.4%)20″ x 6.5-8.5″
295/40R2029.3″ (-2.4%)20″ x 10.0-11.5″
235/45R2129.3″ (-2.4%)21″ x 7.5-9.0″
265/40R2129.3″ (-2.4%)21″ x 9.0-10.5″
265/35R2229.3″ (-2.4%)22″ x 9.0-10.5″
305/30R2229.2″ (-2.7%)22″ x 10.5-11.5″
315/25R2329.2″ (-2.7%)23″ x 11.0-12.0″
265/25R2429.2″ (-2.7%)24″ x n/a

*Disclaimer: Please note that our tire dimensions & measurements are an approximation number, while the tire manufacturers may have different ways in calculating or rounding numbers. We recommend referring to the vehicle manufacturer's manual or checking with the tire technician to find out the correct tire size for your vehicle.

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More tire sizes for 21" Wheel:

26″ Tire Diameter

27″ Tire Diameter

28″ Tire Diameter

29″ Tire Diameter

30″ Tire Diameter

31″ Tire Diameter

32″ Tire Diameter

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