Does The Ply Rating Of A Trailer Tire Matter

Updated 06/27/2019 | Published 06/26/2019

Question:

When both sets of tires e ply rated , why is it that both have the same ply rating for sidewall? 2 ply.... I understand about the so called bigger cords and belts but it is still the same number of plys. Difference between st and lt tires sidewall.

asked by: Jerry D

Expert Reply:

The sidewall is of a ST (special trailer) tire is built with a larger diameter steel wire to meet additional load requirements. The LT (light truck) tire is not designed to carry as much weight as a ST tire can because they are made specifically for trailers. LT tires can sometimes be used on trailers but ST tires are recommended.

Modern trailer tires do not use the same ply rating system that corresponds to load range like they used to. The ply rating doesn't necessarily indicate the actual number of layers of material anymore. Since tire materials have evolved they have become lighter and stronger, which also means less heat build up. Large tire load capacities that may have needed several layers of materials in the past can now be built with less layers compared to years ago. All in all, the ply rating is not as important as it used to be and the weight capacity of the tire is what really matters.

expert reply by: Heather A