315/40R21 Tires

315/40R21 Conversion

When converted to inches, 315/40R21 is equivalent to 30.9x12.4R21.

315/40R21 tire has a section width of 12.4 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 inches (126 mm) is the measurement from the wheel rim to top of the tire tread. Overall diameter of 30.9 inches (785 mm) reflects the outer diameter of the tire and stands for tire height. Circumference of 97 inches (2464.9 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. 315/40R21 tire makes 653 revolutions per mile (406 revolutions per kilometer).

315/40R21 Section Width
12.4"
30.9"
315/40R21 Tire Side
Tire Circumference
97"
21"
5"
653 Revs/Mile
Metric Inches
Overall Diameter (Tire Height) 785 mm 30.9"
Tread Width 315 mm 12.4"
Rim Diameter 533.4 mm 21"
Sidewall Height 126 mm 5"
Circumference 2464.9 mm 97"
Revolutions 406 per km 653 per mile

315/40R21 Replacement Tire Sizes

Replacement tires have to be within 3% of the original tire's overall diameter. 315/40R21 tire can be replaced with 26 compatible tire sizes. Select optional plus size to see its specs.

Tire Size Overall Diameter Difference
295/30R23 30" (762 mm) -2.9%
255/40R22 30" (763 mm) -2.8%
255/45R21 30" (763 mm) -2.8%
295/35R22 30.1" (765 mm) -2.5%
295/40R21 30.3" (769 mm) -2%
265/40R22 30.4" (771 mm) -1.8%
265/45R21 30.4" (771 mm) -1.8%
305/35R22 30.4" (773 mm) -1.5%
275/40R22 30.7" (779 mm) -0.8%
315/35R22 30.7" (779 mm) -0.8%
325/30R23 30.7" (780 mm) -0.6%
275/45R21 30.7" (781 mm) -0.5%
285/35R23 30.9" (784 mm) -0.1%
285/40R22 31" (787 mm) 0.3%
325/35R22 31" (787 mm) 0.3%
285/45R21 31.1" (789 mm) 0.5%
255/45R22 31.1" (789 mm) 0.5%
255/50R21 31.1" (789 mm) 0.5%
295/35R23 31.1" (790 mm) 0.6%
325/40R21 31.2" (793 mm) 1%
295/40R22 31.3" (795 mm) 1.3%
265/45R22 31.4" (797 mm) 1.5%
305/35R23 31.4" (798 mm) 1.7%
305/40R22 31.6" (803 mm) 2.3%
275/40R23 31.7" (804 mm) 2.4%
275/45R22 31.8" (807 mm) 2.8%