Tire Guide and Tips: Understanding your Tire
Type:
P = Passenger Car Tire
LT = Light Truck Tire
Nominal width: Overall width of the tire in millimeters
Aspect ratio: Ratio of sidewall height (from rim to tread) to the tread width
Tire construction:
R = Radial
B = Belted Bias
D = Diagonal Bias
Rim diameter code:Size of the wheel in inches
Load index:weight capacity of the tire(Many tires do not display this on the sidewall.)
Speed symbol: The manufacturer recommends not to exceed this speed(Many tires do not display this on the sidewall.)
R = up to 106 mph
S = up to 112mph
T = up to 118mph
U = up to 124mph
H = up to 130mph
V = up to 149mph
Z = over 149 mph
V and Z rated tires have excellent dry pavement grip and traction, but due to their soft rubber compounds, they have a short life.
Treadwear grade: indicates how long a tire should last
The higher the number, the longer the tire should last. 100 is the basic treadwear rating.
Traction grade: works like grades in school
A = best
B = good
C = acceptable
Temperature grade: works like grades in school
A = best
B = good
C = acceptable
If you drive your car very hard, you want a temperature rating of ‘A’ because a ‘C’ could fail faster under these conditions.