Re: Size does matter!
Fella's the weight is a factor, but if you really want to kill an axle fast, put on a rim with minimal backspacing (pokes the tire a long way out of the fender well, like the idiot lowrider trucks). When I was designing semi-truck trailers we had a customer who was consistently breaking rear axles. After a lot of cajoling we finally discovered that he had taken the duals off of the rear axle and was running a single tire in the outside position. This in effect put a very large moment on the axle. We instructed him to get a rim with more backspacing, to reduce the moment arm, or put the tires to the inside position. He changed the tires, and we never heard of another broken axle. This type of loading is why full float axles are better than and semi floating axle. In a full float situation the weight of the truck acting vertically is carried by the spindle and the axle housing, and only rotational loads have to be transmitted by the axle. In a semi-float situation the axle shaft is forced to do double duty, carrying both the weight and the rotational load. This combined loading situation increases the stress dramatically on the axle, and putting the center of the tire farther from the flange of the axle only serves to amplify an already marginal situation. In the case of the D30, the larger diameter will be worse, because of the fact that you have a much larger lever arm to break the u-joints. Most of the front axles on our Jeeps are full-floating so only the rotational load is carried by the axle shaft. The 35's will take more force to stop and get moving, the polar moment (resistence to rotation, or stopping rotation) is more a function of diameter than weight, to a point, i.e. it takes less force to spin a flywheel that is smaller diameter, even if it weighs the same as a larger diameter diameter flywheel. Even though your 33's weigh more, the weight is probably in the wheel and not the tire, so the 35's would still be worse due to the larger diameter.
Cage Up, Wheels Down
All my Jeeps are in pieces! Except for one!!