Our 24ft Haulmark had torsion flex axles (5K axles). Our current Cargo Mate has leaf springs. Personally, looking under the trailer, it looked like an afterthought the way the leaf perches are welded to boxes welded to the frame. Long story... my dad ordered the trailer. I told him to absolutely get the big axles, and 16" wheels. It showed up with 15" wheels. He was going to accept it, until we discussed once again the tire he77 I'd been living..... so, he took the trailer back to where he bought it. From there I have no idea what happened.... other than it had 16" wheels (six lug 16" wheels on 5K axles) the first time I saw it. We got 4 years out of the first set of tires, but most of that was short trips to the local track with a couple long treks from SoDak to our home in AZ. The current set of tires have only been on a little over a year and the outer edge is wearing badly on a couple.... right rear seems to be the worst.