| Tire Size | Diameter | Rim (H x W) |
| 245/30R24 | 29.8″ (+2.7%) | 24″ x n/a |
| 275/45R20 | 29.7″ (+2.4%) | 20″ x 8.5-10.5″ |
| 245/45R21 | 29.7″ (+2.4%) | 21″ x 7.5-9.0″ |
| 275/40R21 | 29.7″ (+2.4%) | 21″ x 9.0-11.0″ |
| 315/35R21 | 29.7″ (+2.4%) | 21″ x 10.5-12.5″ |
| 245/50R20 | 29.6″ (+2%) | 20″ x 7.0-8.5″ |
| 305/40R20 | 29.6″ (+2%) | 20″ x 10.0-12.0″ |
| 275/35R22 | 29.6″ (+2%) | 22″ x 9.0-11.0″ |
| 265/45R20 | 29.4″ (+1.4%) | 20″ x 8.5-10.0″ |
| 305/35R21 | 29.4″ (+1.4%) | 21″ x 10.0-12.0″ |
| 315/30R22 | 29.4″ (+1.4%) | 22″ x 10.5-11.5″ |
| 275/25R24 | 29.4″ (+1.4%) | 24″ x 9.5-10.0″ |
| 235/50R20 | 29.3″ (+1%) | 20″ x 6.5-8.5″ |
| 295/40R20 | 29.3″ (+1%) | 20″ x 10.0-11.5″ |
| 235/45R21 | 29.3″ (+1%) | 21″ x 7.5-9.0″ |
| 265/40R21 | 29.3″ (+1%) | 21″ x 9.0-10.5″ |
| 265/35R22 | 29.3″ (+1%) | 22″ x 9.0-10.5″ |
| 305/30R22 | 29.2″ (+0.7%) | 22″ x 10.5-11.5″ |
| 315/25R23 | 29.2″ (+0.7%) | 23″ x 11.0-12.0″ |
| 265/25R24 | 29.2″ (+0.7%) | 24″ x n/a |
| 145/80R20 | 29.1″ (+0.3%) | 20″ x n/a |
| 295/35R21 | 29.1″ (+0.3%) | 21″ x 10.0-11.5″ |
| 255/45R20 | 29″ (Equal) | 20″ x 8.0-9.5″ |
| 285/40R20 | 29″ (Equal) | 20″ x 9.5-11.0″ |
| 325/35R20 | 29″ (Equal) | 20″ x 11.0-13.0″ |
| 255/35R22 | 29″ (Equal) | 22″ x 8.5-10.0″ |
| 295/30R22 | 29″ (Equal) | 22″ x 10.0-11.0″ |
| 305/25R23 | 29″ (Equal) | 23″ x 10.5-11.5″ |
| 255/25R24 | 29″ (Equal) | 24″ x n/a |
| 285/35R21 | 28.9″ (-0.3%) | 21″ x 9.5-11.0″ |
| 245/35R22 | 28.8″ (-0.7%) | 22″ x 8.0-9.5″ |
| 245/25R24 | 28.8″ (-0.7%) | 24″ x n/a |
| 245/45R20 | 28.7″ (-1%) | 20″ x 7.5-9.0″ |
| 275/40R20 | 28.7″ (-1%) | 20″ x 9.0-11.0″ |
| 315/35R20 | 28.7″ (-1%) | 20″ x 10.5-12.5″ |
| 245/40R21 | 28.7″ (-1%) | 21″ x 8.0-9.5″ |
| 325/30R21 | 28.7″ (-1%) | 21″ x 11.0-12.0″ |
| 285/30R22 | 28.7″ (-1%) | 22″ x 9.5-10.5″ |
| 275/35R21 | 28.6″ (-1.4%) | 21″ x 9.0-11.0″ |
| 335/25R22 | 28.6″ (-1.4%) | 22″ x 11.5-12.5″ |
| 275/30R22 | 28.5″ (-1.8%) | 22″ x 9.0-10.0″ |
| 305/35R20 | 28.4″ (-2.1%) | 20″ x 10.0-12.0″ |
| 315/30R21 | 28.4″ (-2.1%) | 21″ x 10.5-11.5″ |
| 235/45R20 | 28.3″ (-2.5%) | 20″ x 7.5-9.0″ |
| 265/40R20 | 28.3″ (-2.5%) | 20″ x 9.0-10.5″ |
| 265/35R21 | 28.3″ (-2.5%) | 21″ x 9.0-10.5″ |
| 265/30R22 | 28.3″ (-2.5%) | 22″ x 9.0-10.0″ |
| 305/30R21 | 28.2″ (-2.8%) | 21″ x 10.5-11.5″ |
| 315/25R22 | 28.2″ (-2.8%) | 22″ x 11.0-12.0″ |
| 265/25R23 | 28.2″ (-2.8%) | 23″ x 9.5-10.0″ |
255/40R21 In Inches – Tire Size & Rim Fitment Guide
What size tire is 255/40R21 in Inches?
The 255/40R21 tire has an overall diameter of 29 inches, a section width of 10 inches, and can be mounted on 21 x 8.5-10.0 inches rim. The equivalent tire size in the high flotation system is 29x10R21.
| Inches | Millimeters | |
| Tire Diameter | 29 | 737.4 |
| Section Width | 10 | 255 |
| Rim Height | 21 | 533 |
| Sidewall Height | 4 | 102 |
| Circumference | 91.2 | 2316.6 |
10"
29"
91.2"
21"
4"
694.7 Revs/Mile
To easy understanding, let us break down each component of the 255/40R21 tire size to know what these numbers represent and how they may affect your vehicle's performance:
How tall is a 255/40R21 tire?
A 255/40R21 tire has a height of 29 inches (737.4 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 no load.
How wide is a 255/40R21 tire?
The 255/40R21 has a width of 10 inches (255 mm). This is the tire measurement at its thickest point, the distance between the inner sidewall’s and the outer sidewall’s widest point, also known as section width or tread width.
255/40R21 sidewall height
The sidewall height of a 255/40R21 is 4 inches (102 mm). It’s measured from the rim to the outer edge of the tire's tread, expressed as a percentage of tire width.
What size rim do I need for 255/40R21 tire?
You can put on a rim with a height of 21 inches and a rim width ranging from 8.5-10.0 inches for a 255/40R21 tire. (Based on recommendations of The Tire and Rim Association (TRA))
Putting very wide tires on narrow rims or vice versa can result in reduced performance of the tire.
255/40R21 circumference
The 255/40R21 tire has a circumference of 91.2 inches (2316.6 mm), This is the measurement of the distance the tire covers in one full rotation.
The tire circumference plays a crucial role in your vehicle's overall performance, affecting its speedometer accuracy, acceleration and fuel efficiency.
255/40R21 Revolutions
The 255/40R21 performs 694.7 revs/mile. Revolutions per mile indicate the number of times a tire rotates while it covers the distance of one mile.
Alternative Tire Sizes for 255/40R21
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 255/40R21:
*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.