IF you are not rotating the tires, front to rear etc, then having an E rated tire ont he rear, a D up front, is not an issue. I bought an 81 C2500 that was this way, door panel tire load had it this way.......Did this on a 1 ton dually I had too. Then again, I am usually running traction tires on the rear, hwy front on the RWD rigs to.
As far as trailer sway.....uncontrolled fishtail? maybe heavier duty rears on the truck may help. Is the tongue mounted level or slightly low - if high this will cause sway. what is the hw % - this maybe too low %, If it is moving side to side with cross winds, that can/should be normal, IF the whole unit moves as one. The sway issues may not be the tires.....then again, some have had sway due to tires also, not as common.
Marty
