A load range E tire, used on light trucks and RVs, can have two or three fabric plies or one steel ply. The E rating indicates how much weight the tire can hold based on the strength of 10 fabric plies. Many tire shops still call them E-10 tires.
Pickup trucks or vans with at least a 3/4-ton rating need E-10 tires to support their payloads. The load rating and ply count on E-10 RV-specific tires are the same as those on tires designed for light trucks. On RVs, it is common practice to put a tire with a straight rib on the front to help with steering and a knobbed tire on the back to provide better traction.