Something was drastically wrong if a tire wore out in 2000 miles of trailering. That was a cheap tire issue, not a bias or radial issue. Those Marathons STs still move around a lot more than bias tires and will show it big when you have an unbalanced rig or emergency stop. I replaced old bias tires with Marathons and had massive sway that never happened before. Changing the rigs weight and balance helped but not enough to make it track straight like bias tires. I took them off in a matter of weeks and replaced back with bias trailer tires. I didn't like eating the cost but it was that much difference in the scare factor. Premium bias trailer tires cost more than the Marathons too. That was on a 20' Proline outboard with a properly sized trailer towed behind a full size American V8 auto with self adjusting air shocks. That was a 4500lb boat rig and I doubt a 15 Mont would move the car around no matter how much give the tires had...but I thought sharing the info was a good idea anyway.