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.....)