What does the print on the
sidewall of your tire tell you:
The Metric tire size code
consists of a string of letters and numbers, as
3 digit number: The "nominal section width" of the
tire in millimeters; the widest point from both
outer edges (side wall to side wall).
An optional letter (or letters) indicating the
intended use or vehicle class for the tire:-
P: Passenger Car
LT: Light Truck
ST: Special Trailer
T: Temporary (restricted usage for "Space-Saver"
/: Slash character for character separation.
2 or 3 digit number: The "aspect ratio" of the
sidewall height as a percentage of the total width
of the tire.
An optional letter indicating construction of the
fabric carcass of the tire:
B: bias belt (where the sidewalls are the same
material as the tread, leading to a rigid ride)
1 or 2 digit number: Diameter in inches of the wheel
that the tires are designed to fit.
2 or 3 digit number: Load index
1 or 2 digit/letter combo: Speed rating
Some light truck tires
follow the Light Truck Numeric or Light Truck High
Flotation systems, indicated by the letters LT at
the end instead of the beginning of the sequence, as
The tire diameter is given for High Flotation tires
and omitted from Numeric tires.
2 digit number: The diameter of the tire in inches.
x: Separator character.
3 or 4 digit number: The section width (cross
section) of the tire in inches.
Construction of the fabric of the tire:
B: bias belt
2 digit number: Diameter in inches of the wheel rim
that this tire is designed to fit.
LT: Designates that this is a Light Truck tire.
Load index and speed rating are sometimes not
mandatory for flotation sizes, but must be for any
tire approved for street and highway use.
2 or 3 digit number: Load index.
1 or 2 digit/letter combination: Speed rating.
Load Range (plies)
The Load Range Letter on
light truck tires indicates their ply rating.This
letter indicates the load carrying capacity of the
tire in terms of its construction. A "C" indicates
the tire has a 6-ply load carrying capacity. The
tire is not actually built with 6 plies, but
contains one or two plies of equivalent strength. A
"D" is an 8-ply rating, and an "E" is a 10-ply
rating. If there is no letter, the tire has a
standard 4-ply rating.