It is possible to put truck tires on a passenger vehicle as their prevalent use on SUVs demonstrates. And it is possible to put car tires on a trailer, though this isn’t recommended because of the differences between them. Let’s learn how truck tires differ from car tires.
Light truck tires have an LT on the side of the tire. Passenger tires are labeled with a P. These are sometimes called P-metric tires. However, there are far more differences between truck and car tires.
LT or light truck tires have larger gauge cords inside of them so that they can handle the heavier loads that come with both empty and loaded trucks. LT tires often but do not always have an extra steel belt inside. Truck tires almost always have more rubber in the sidewall.
LT tires typically have a deeper tread to maintain a tight grip on the road despite their load. Light truck tires either 8 or 10 ply. Eight ply tires have load range D, while ten ply tires are load range E. In contrast, passenger tires always have a four ply rating.
Load Index/Load Rating
You may not be familiar with load ratings, because passenger tires don’t have one. They always have four ply material, and this means they aren’t on the alphabetical load rating system. However, passenger tires may be rated as SL for standard load or XL (extra load) or reinforced. A standard load tire can withstand 36 PSI, while an extra load or XL tire can stand a load up to 42 PSI. If in doubt, go for the better tires. This advice applies to the tires for your truck too.
Light truck tires have a much wider load range. For example, the C1 light truck load rating has a maximum tire pressure at 50 PSI under load. C2 tires can only stand a tire pressure of 35 PSI. D1 tires are 8 ply. They have a 65 max tire pressure of 65 PSI. D2 tires can stand 65 PSI under full load. E tires are 10 ply. E1 can stand 80 PSI under maximum load. F1 tires are rarely used on light trucks, but they’re 12 ply and rated for 95 PSI. G class truck tires are rugged 14 ply tires and can function at up to 110 PSI.
The load index is a numerical scale. For example, the load index of 0 equals a carrying capacity of 99 pounds. A load index of 10 equates to a 132 pound load that the tire can withstand. A load index of 50 translates to a carrying capacity of 419 pounds. A load index of 100 means the tire has a carrying capacity of 1761 pounds per tire. When determining the carrying capacity each tire must withstand, first determine how much your trailer and full load will weight. Multiply this by 20 percent to give yourself margin. Then divide that value by the number of tires. For example, if you have 2 tires on the trailer, divide a total load weight by 2. If the RV has 4 tires, divide the weight of the vehicle, passengers and load by four, taking that 20 percent margin into effect. The carrying capacity value you get is the lowest load that the tires need to carry. You cannot go wrong by buying tires that can carry far more weight than you intend to put on them.