When converted to inches, 325/40R21 is equivalent to 31.2x12.8R21.
325/40R21 tire has a section width of 12.8 inches which is the measurement of tire's width from its inner sidewall to its outer sidewall. Rim diameter of 21 inches represents the size of the wheel the tire can be mounted on. Sidewall height of 5.1 inches (130 mm) is the measurement from the wheel rim to top of the tire tread. Overall diameter of 31.2 inches (793 mm) reflects the outer diameter of the tire and stands for tire height. Circumference of 98 inches (2490 mm) is the outer perimeter of the tire. Tire revolutions indicate the number of times a tire revolves while it covers the distance in miles or kilometers. 325/40R21 tire makes 647 revolutions per mile (402 revolutions per kilometer).
Overall Diameter (Tire Height)
402 per km
647 per mile
Best Prices on 325/40R21 Tires
325/40R21 Replacement Tire Sizes
Replacement tires have to be within 3% of the original tire's overall diameter. 325/40R21 tire can be replaced with 25 compatible tire sizes. Select optional plus size to see its specs.