June 1st, 2015

Today we are going to talk about ST (trailer tires) vs passenger tires. Trailers are attached and follow the vehicle down the road and the 2 main concerns are traction and swaying back and forth making it difficult to drive straight down the road. High center of gravity and heavy loads accelerate the sway. ST tires are built on stiffer casings with extra plys and have higher air pressure capability and higher payload than a passenger tire….with this being said ST tires will help reduce the sway on the trailers and make pulling a trailer a lot easier for the driver. By the way ST and LT tires can be used on trailers and will carry their full weight rating listed on the tire. But I think in my example below it points out that you should only use ST tires on trailers for no other reason than load carrying capacity. Passenger tires being used on trailers with their flexible sidewalls will increase trailer sway and their load carrying capacity listed on the sidewall has to be reduced by 9% because it’s used on a trailer. Yes the answer here is don’t put a passenger tire on a trailer….see below

St225/75r15 6 ply max 50psi….carries 2540 lbs.
LT225/75r15 6 ply max 50psi…..carries 1880 lbs.
P225/75r15 standard load max 44lbs…carries 1874 lbs.…..-9% is 1705 lbs. difference between ST and passenger is 835 lbs. and ST has a stiffer sidewall

Note: the LT tire can be used on trailers but has same load rating as passenger tire it’s also good here to note that trailer tires: ST are designed for speeds under 65mph…if you go faster you should add 10 psi to the existing cold inflation pressure being used and shouldn’t exceed 75 mph.

Also note here that you should never use a trailer tire on an LT or passenger vehicle ….I think most even state on the sidewall for trailer use only.

I think that’s enough said for trailer tires!!