Understanding Tires

Bias Ply Tire: A pneumatic tire in which the ply cords that extend to the beads are laid at alternate angles substantially less than 90 degrees to the center-line of the tread.

Example – ST205/75D15

Radial Ply Tire: A pneumatic tire in which the ply cords that extend to the beads are laid at substantially 90 degrees to the center-line of the tread.

Example – ST205/75R15

Load Rating: The maximum load that a tire is rated to carry for a given inflation pressure.

Tire Ply: Is the number of layers of rubber coated fabric in the tire.

Load Range: (Load range = 2ply/ Letter) Letters are used to identify a given size tire with its load and inflation limits, when used in a specific type of service.

Example: Load Range D tire = 8 ply or Load Range C = 6 ply

Tires/ Tire Pressure: – Always use the proper size tire/weight rating for the trailer & maintain manufacturers recommended tire pressure.

Recommended inflation pressure is provided by the vehicle manufacturer on the tire sidewall and on the Certification / VIN tag, which is usually located at the front left side of the trailer.