P:
The “P” indicates the tire is for passenger vehicles.
Next number:
This three-digit number gives the width in millimeters of the tire
from sidewall edge to sidewall edge. In general, the larger the number, the wider
the tire.
Next number:
This two-digit number, known as the aspect ratio, gives the tire’s
ratio of height to width. Numbers of 70 or lower indicate a short sidewall for
improved steering response and better overall handling on dry pavement.
R:
The “R” stands for radial. Radial ply construction of tires has been the industry
standard for the past 20 years.
Next number:
This two-digit number is the wheel or rim diameter in inches. If
you change your wheel size, you will have to purchase new tires to match the new
wheel diameter.
Next number:
This two- or three-digit number is the tire’s load index. It is
a measurement of how much weight each tire can support. You may find this
information in your owner’s manual. If not, contact a local tire dealer. Note: You
may not find this information on all tires because it is not required by law.
M+S:
The “M+S” or “M/S” indicates that the tire has some mud and snow
capability. Most radial tires have these markings; hence, they have some mud and
snow capability.
Speed Rating:
The speed rating denotes the speed at which a tire is designed to be
driven for extended periods of time. The ratings range from 99 miles per hour
(mph) to 186 mph. Note: You may not find this information on all tires because it is
not required by law.
*
For tires with a maximum speed capability over 149 mph, tire manufacturers
sometimes use the letters ZR. For those with a maximum speed capability over 186
mph, tire manufacturers always use the letters ZR.
U.S. DOT Tire Identification Number
This begins with the letters “DOT” and indicates that the tire meets all
Nominal width of
tire in millimeters
Radial
Ratio of height to
width (aspect ratio)
Max.
permissable
inflation
pressure
Passenger
car tire
Treadwear, traction
and temperature grades
Max. load rating
Tire ply
composition
and materials
used
Sever snow
conditions
U.S. doT tire
identification number
load index &
speed symbol
Rim diameter
code