315/40R21 In Inches – Tire Size & Wheel Fitment Guide

What size tire is 315/40R21 in Inches?

The 315/40R21 tire has an overall diameter of 30.9 inches, a section width of 12.4 inches, and can be mounted on 21 x 10.5-12.5 inches rim. The equivalent tire size in the high flotation system is 30.9x12.4R21.

Tire Diameter30.9785.4
Section Width12.4315
Rim Height21533
Sidewall Height5126
tire diameter
Tire Side
Tire Circumference
652.2 Revs/Mile

To easy understanding, let us break down each component of the 315/40R21 tire size to know what these numbers represent and how they may affect your vehicle's performance:

How tall is a 315/40R21 tire?

The 315/40R21 tire has a width of 12.4 inches (315 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: 12.4 In.

How wide is a 315/40R21 tire?

The 315/40R21 tire has a height of 30.9 inches (785.4 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: 30.9 In.

315/40R21 sidewall height

The 315/40R21 has a sidewall height of 5 inches (126 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: 5 In.

What size rim do you need for 315/40R21 tire?

You can mount the 315/40R21 tire on a rim with a height of 21 inches and a rim width ranging from 10.5-12.5 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: 10.5-12.5 In.

315/40R21 circumference

The 315/40R21 tire has a circumference of 97.1 inches (2467.4 mm), This is the measurement of the distance the tire travels in one revolution.

The tire circumference plays a crucial role in your vehicle's overall performance, affecting its speedometer acceleration, accuracy and fuel efficiency.

Circumference: 97.1 In.

315/40R21 Revolutions

The 315/40R21 performs 652.2 revs/mile. Revolutions per mile indicate the number of times a tire rotates while it covers the distance of one mile.

652.2 revs/mile

Replacement Tire Sizes for 315/40R21

As a rule, you can replace the tire within a 3% difference in tire diameter (height) of the OEM tire size. However, it should be considered as a general guideline, not a hard and fast rule. Here is a list of compatible tire sizes for 315/40R21:

Tire SizeDiameterRim (H x W)
275/50R2131.8″ (+2.8%)21″ x 7.5-9.5″
295/25R2631.8″ (+2.8%)26″ x 10.0-11.0″
275/45R2231.7″ (+2.5%)22″ x 8.5-10.5″
275/40R2331.7″ (+2.5%)23″ x 9.0-11.0″
245/60R2031.6″ (+2.2%)20″ x 7.0-8.5″
295/50R2031.6″ (+2.2%)20″ x 8.0-10.5″
305/40R2231.6″ (+2.2%)22″ x 10.0-12.0″
265/55R2031.5″ (+1.9%)20″ x n/a
265/45R2231.4″ (+1.6%)22″ x 8.5-10.0″
305/35R2331.4″ (+1.6%)23″ x 10.0-12.0″
315/30R2431.4″ (+1.6%)24″ x 10.5-11.5″
275/25R2631.4″ (+1.6%)26″ x 10.0″
295/40R2231.3″ (+1.3%)22″ x 10.0-11.5″
285/50R2031.2″ (+1%)20″ x 8.0-10.0″
325/40R2131.2″ (+1%)21″ x 11.0-13.0″
235/60R2031.1″ (+0.6%)20″ x 6.5-8.5″
285/45R2131.1″ (+0.6%)21″ x 9.0-10.5″
295/35R2331.1″ (+0.6%)23″ x 10.0-11.5″
255/55R2031″ (+0.3%)20″ x 7.0-9.0″
255/50R2131″ (+0.3%)21″ x 7.0-9.0″
255/45R2231″ (+0.3%)22″ x 8.0-9.5″
285/40R2231″ (+0.3%)22″ x 9.5-11.0″
325/35R2231″ (+0.3%)22″ x 11.0-13.0″
295/30R2431″ (+0.3%)24″ x 10.0-11.0″
355/25R2431″ (+0.3%)24″ x n/a
285/35R2330.9″ (Equal)23″ x 9.5-11.0″
275/50R2030.8″ (-0.3%)20″ x 7.5-9.5″
305/45R2030.8″ (-0.3%)20″ x 9.5-11.5″
275/45R2130.7″ (-0.7%)21″ x 8.5-10.5″
275/40R2230.7″ (-0.7%)22″ x 9.0-11.0″
315/35R2230.7″ (-0.7%)22″ x 10.5-12.5″
325/30R2330.7″ (-0.7%)23″ x n/a
285/30R2430.7″ (-0.7%)24″ x 9.5-10.5″
295/45R2030.5″ (-1.3%)20″ x 9.5-11.0″
275/30R2430.5″ (-1.3%)24″ x 9.0-10.0″
265/50R2030.4″ (-1.6%)20″ x 7.5-9.5″
265/45R2130.4″ (-1.6%)21″ x 8.5-10.0″
305/35R2230.4″ (-1.6%)22″ x 10.0-12.0″
295/40R2130.3″ (-2%)21″ x 10.0-11.5″
265/40R2230.3″ (-2%)22″ x 9.0-10.5″
235/55R2030.2″ (-2.3%)20″ x 6.5-8.5″
285/45R2030.1″ (-2.7%)20″ x 9.0-10.5″
295/35R2230.1″ (-2.7%)22″ x 10.0-11.5″
255/50R2030″ (-3%)20″ x 7.0-9.0″
255/45R2130″ (-3%)21″ x 9.5-11.0″
285/40R2130″ (-3%)21″ x 9.5-11.0″
255/40R2230″ (-3%)22″ x 8.5-10.0″
295/30R2330″ (-3%)23″ x 10.0-11.0″
255/30R2430″ (-3%)24″ x 8.5-9.5″

*Disclaimer: The tire size is for information purposes only, the measurement is an approximation, as tire manufacturers can have slight variations in their measurements. It's recommended to refer to the vehicle manufacturer's guidelines or consult with a tire mechanic to determine 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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