The first number is the tire width in millimeters. The 2nd number is used to calculate the sidewall height or "aspect ratio" , by percentage. So, the sidewall height of a The 3rd number (generally preceded by an "R") is Rim Diameter in inches. This is the diameter of the rims bead seat base, not the diameter of the outer rim edge.
The numeral 215 is for the tire width in millimeters. The number 65 is the aspect ratio of this tire. The R stands for radial, as opposed to diagonal or belted tires. The 15 stands for inches, not millimeters, and it is the measurement of the rim diameter.
Related posts to tire diameter chart
Tire Size Chart. To calculate a metric tire size into inches you multiply the first number by the second number devided by 100 which gives you the sidewall height in millimeters, divide it by 25.4 to convert it to inches. The overall diameter is then the wheel diameter plus 2 sidewall measurements, and divide the first number by 25.4 to calculate .
The 255 is the tire width in millimeters, measured from the bottom of the bead to the bottom of the bead, the 60 is the sidewall aspect ratio the tire width factor , the ratio of sidewall height to tire width at the tread indicating that the sidewall height is 70 of the tread width , and the 17 is the wheel rim diameter in inches..
Tire Tech Information Tire Size Guide. Width, tire Overall Diameter of 710 mm and a 460A mm rim diameter, with the “A” in 460A signifying these tires feature “asymmetric” beads in which the outside bead 450 mm and inside bead 470 mm are actually different diameters..
139 rows 0183 32 Tire Diameter Chart information from Discount Part Center.