My 14' x 5' stock combo CM trailer came w/ 225(or 215; never can remember, and, it's not sitting here in the room w/ me!)/75R 15 M&S(?) Firestone? tires. They are still on it, though near needing replacement, after @ 16-17 years of ownership...most of the time outside, though 'usually' covered or oriented to take advantage of the 'least' exposure to sun(via direction the trailer is parked.)To be fair, I should add that I never hauled more than two 15 H. 'fullsized' horses in it, and that,only seldom...using it almost entirely to haul either one fullsized or several minis, plus my carriage(s) or carts--so never 'fullly' loaded, weightwise. Always keep these tires at 'max' air pressure, rotate myself, bearings lubed, etc., at recommended intervals by nearby trailer dealership. I pull w/ a '99 F-250 SD 4 WD ext. cab, and usually don't go over 65 when pulling the trailer. I can't complain....

Margo in NM(aka olehossgal)