RV is up on site in the mountains....will double check next trip up there. I do know the tires are premium versus standard, not exactly sure of the nomenclature, but will check. I did max them out to cold pressure capacity before leaving on our last trip. Also, "weight" and "age", regardless of remaining tread play a role as well. My unit is under 10,000 lbs empty. My rig is brand new....since 70 on the highway is my "comfort zone maximum"; I am not concerned....However, I WILL check for knowledge, but at my age, I may forget before I get back home !