maxpower - most tires may be pretty well made, but Marathons (in my experience) are not. I check tire pressure every two weeks unless visibly low. The marathons that were on my OBV trailer were cracking and bulging at two years. That seems premature to me. I've never tried Carlisles, but I did this time to see how they hold up compared to marathons. If marathons are the standard for trailer tires, that's pretty sad.