Not all LT tires are 10 ply. LT tires are available in everything from load range B to load range F, representing the equivalent ply rating range of 4 to 12 ply. To make sure you are purchasing 10 ply LT tires, look for the LT symbol, and the load range E, which is equivalent to 10 ply. You can find this information in the description of the tire, or branded onto the sidewall.