The Adam Blaster
Expedition Leader
Now, I could see that the E-rate might be a bit more resistant to abuse if the argument is that the sidewalls are stronger, because they have to be to support the additional weight that the E-rated tire is designed to handle.
The cords and belts that make up a 10-ply are either thicker, or packed more densely together, or are more numerous, or all of the above. The sidewalls can also be thicker.
There is simply more material present that a foreign object has to push through to get to the inside of the tire and cause a failure.