Tire Size Calculator
Calculate tire sizes in inches or millimeters and find alternative sizes.
Inches
Millimeters
Results for 315/30R21 Tires
Diameter
28.4"
Width
12.4"
Sidewall
3.7"
Circumference
89.3"
Revs per mile
709
Alternate Tire Sizes
21"
15"
16"
17"
18"
19"
20"
22"
23"
Tire Size
Diameter
Width
Sidewall
Circumference
Revs per mile