TIRE 101 - Know Your Tyre (Tire 101)


Tire Type
P = Passenger    LT = Light Truck   T = Temporary spare   ST = Special trailers

Tire Width
3-digit number that gives the approximate tire width in mm. It measures from sidewall to sidewall. 
Typically, the higher the number the larger the tire.

Aspect Ratio
2-digit number that gives the approximate sidewall height. It is expressed as a % of the tire width.
The lower the ratio, the smaller the sidewall height.

R = Radial Ply    B = Bias Ply
Radial tires are the industry standard and refers to the internal belts being 90 degrees to the direction of travel

Wheel Diameter
2-digit number (in inches) that indicates the tire is designed to fit on a wheel with a 16-inch diameter.


Load Index
2-digit number that indicates how much weight the tire is certified to carry at maximum safe inflation.


Speed Rating
1 letter or 1 letter/number combo which indicates the top speed at which a tire is certified under specified conditions.