Tshan, I too am more concerened about the glass than the steel. Either way the bigger factor may be the bumps and pot holes in the road, the rail road tracks, the cattle guards, the graveled roads. It isn't the smooth road that wears out a car's suspention. I went out and bounced on one side of the TheMightyHobie18 trailer with my 150 pounds (56 KG) and i don't think it moved up and down an inch (2.5 cm). Of course it depends on how much weight one carries around in the cat box, but it just seems like it's too stiff for something that is designed to float in water. wondering, Will Lints