Ply Rating | Load Range | Why aren’t there any odd numbers? Since you have to have at least two plies to have a “bias” arrangement, bias ply tires always had an even number of plies. Is cotton still used? Cotton went away a long time ago. One of the major improvements was making plies out of nylon. Nylon is so much stronger that if you’re old enough, you may remember seeing your tires stamped with the words, “2 Ply/4 Ply Rating.” That meant there were only two nylon plies, but they were so strong the tire was equivalent to one made of four cotton plies. And that’s about when things started to get complicated. How so? Ply materials continued to improve, especially with the introduction of steel ply materials and radial construction, making the old Ply Number less and less meaningful. And that resulted in the newer designation we use today, called “Load Range.” On the chart, you can see how today’s Load Ranges correspond to the older Ply Rating system. And why isn’t there an “I” or a “K” Load Range? |
2 | A | |
4 | B | |
6 | C | |
8 | D | |
10 | E | |
12 | F | |
14 | G | |
16 | H | |
18 | J | |
20 | L |
Size | Maximum Single Load (lbs.) | Inflation Pressure (psi) |
295/75R22.5 | 6175 | 110 |
285/75R24.5 | 6175 | 110 |
11R22.5 | 6175 | 105 |
11R24.5 | 6610 | 105 |
12R22.5 | 6610 | 105 |
12R24.5 | 7160 | 105 |
Size | Maximum Single Load (lbs.) | Inflation Pressure (psi) |
295/75R22.5 | 6610 | 120 |
285/75R24.5 | 6780 | 120 |
11R22.5 | 6610 | 120 |
11R24.5 | 7160 | 120 |
12R22.5 | 7390 | 120 |
12R24.5 | 7830 | 120 |