Another Trailer Tire Question

[TJ Moose]

I bought a used utility trailer for cheap (18' flatbed tandem), and 2 of the tires on it are various and sundry used auto tires. Not even the same sizes, I'm ashamed to say, but you know how $$ (or lack thereof) dictate some choices - including getting matching tires. The other 2 tires are trailer tires, which of course say "don't use for any purpose except for towing." I understand the optimum scenario is to have tires of matched size and construction. BUT - the real question - what is the difference between regular auto/truck use tires and trailer tires. Is it a problem using auto tires on a trailer, as long as weight ratings/air pressure considerations are properly observed and maintained? (As they say - enquiring minds want to know.....)

[MartyB]

Used is one way to go, if you can find two of them. I would try to get a ST trailer or an LT truck tire, BEFORE getting a P metric. A P metric is derated some 9-10% over the sidewall rating when use in a truck or trailer use. I have also seen amounts as highas 40% derated, but 9% seems to be the most common.

If you are not hauling to the max of the trailer, then do not worry, but if maxing out the capacity, then get some good used ST or LT tires of equal size.