GarageCalc What 325/60R20 means
325 is the section width in millimeters (12.8 in). 60 is the aspect ratio: the sidewall is 60 percent of the width, so 325 × 0.60 = 195 mm (7.7 in). R is radial construction, and 20 is the wheel diameter in inches (508 mm). Stack two sidewalls on the wheel and you get the overall diameter: 508 + 2 × 195 = 898 mm, or 35.4 in.
A full marking adds a load index and speed rating after the size, for example 325/60R20 91V. Those two codes set how much weight and speed the tire is certified for; look them up in the load index chart and the speed rating chart.
Plus and minus sizing from 325/60R20
Similar diameter does not establish interchangeability. Follow the vehicle manufacturer's approved sizes; see Michelin's tire-size guidance.
No common size on a 19 or 21-inch wheel stays within 3 percent of 35.4 in, so 325/60R20 is best replaced like for like. The comparison calculator compares nominal dimensions for any candidate.
Frequently asked questions
How tall is a 325/60R20 tire?
35.4 inches (898 mm) in overall diameter: the 20-inch wheel (508 mm) plus two 195 mm sidewalls. Actual dimensions depend on the tire model, tread depth, pressure and load; check the tire manufacturer specifications.
What is 325/60R20 in inches?
35.4 x 12.8 R20: 35.4 inches tall, 12.8 inches wide, on a 20-inch wheel. The sidewall is 7.7 inches and the circumference is 111.1 inches, so the tire turns 570 times per mile.
What tire sizes are equivalent to 325/60R20?
Within 3 percent of the same diameter on the same 20-inch wheel: 305/60R20 (-2.7%). The percentage is the diameter change, which is also your speedometer error.