Oversize tires should not make any difference. I run 35x12.5 with not abnormal wear. I also don't run more than 26 lbs on the street (10-12 lbs off road).
My suggestion would be to get a 4-wheel alignment (just a front alignment will not do it).
Why? A front alignment will correct tire wear problems, as long as the vehicle is not towed. If the rear axle is not square with the front wheels and the front alignment is done, the vehicle will go down the road crab-wise. "Crab-wise" is a technical term that means the front axle is a little to the left or right of rear axle. Again, if not towing, this will be fine. However when you hook up the front bumper is going to be held rigidly square to the direction of travel, if the rear axle is not square to the front axle (actually the front bumper) the tires will not be rolling square and will scrub the rubber. The cupping is caused by the grabbing and releasing of the tire as it is pulled down the road.
Sometimes this behavior is significant enough to push the towing vehicle around. Especially the Workhorse leaf spring chassis with no track bars.
Seems like I need to do a diagram so that this is easier to understand.
2002 35R Southwind, W22 8.1L Vortec UltraPower, 19.5' wheels
Toad: Wrangler, lifted and on 35" tires