What do the tire size numbers mean?

Question

Which number refers to what measurement and what unit of measurement is used? And what are the letters for?

my tire is P245/60/R15. 15 refers to the rim size, right? Well, what's the rest of it?

Answer 1

First: The letter(s)
'P' - Passenger vehicle
'LT' - Light truck
'ST' - Special trailer
'T' - Temporary

Then:
The width of the tire - in millimeters, from sidewall edges

A slash character ('/').

The ratio of the sidewall height to the total width of the tire as a percentage.

Construction of the fabric of the tire
'B' - bias belt
'D' - diagonal
'R' - radial

Diameter of the rim that this tire is designed to fit - in inches.

So you are passenger car, 245 mm from edgewall to edgewall, 60% ratio height to width, radial, with 15 inch rims.

Answer 2

p means it is a passenger car rated tire; 245 is a metric (millimeter) measurement acroos the tread face of the tire; and the 60 means it is 60% of the 245 when you measure it from the wheel out to the tread.
At least that is what it is supposed to mean, as one companys tire of that size may, for whatever reason, be different from another companys. Always match your tires in pairs, front or rear, by the brand name. Hope that helps!

Answer 3

Go to tire mfg site (Cooper etc). Look and find explanation of what each number means right there on the web.

Answer 4

go to this site and it will give you a complete explaination of tire sizes.

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=46

These guys also sell great tires cheap.