So my friend got some wheels for his Evo from another car (350Z) which are 19x8 front and 19x9 rear. They fit but he needs to roll the rear (wants to keep the wider ones in the rear).

Anyway, right now they have different tires on them so he plans on putting 235/35/19 all the way around. I was thinking the additional inch that the sidewalls need to travel in order to make a bead with the wheel would reduce the overall diameter of the rear tires, causing accelerated differential wear. He has a IX with ACD. If anyone knows whether this will be a problem, please chime in. Thanks in advance.

If he will be running the same size tire on all 4 corners there should be no problems. BozzSpeed runs a 9.5" up front and an 8.5" rear on their Evo6, but 255/40/17 size tires are on all 4 wheels.
The idea is that the more rounded tire in the rear will cause progressive breakout for handling closer to a RWD car.
The problem that your friend may encounter with a rounded tire in the front is increased understeer.

u run the reverse stagger on the evos. thus the wider wheel up front for better turn in and cornering. but it will only work and not damage your car if you have the same tires all around.

yes like jondeamnd said, you don't want to run the wider wheels in the back, but in front. however, keep in mind this means that if you run the same tire size, the front tires will be stretched more on the wider wheels, and this is not really ideal, possibly for handling but also especially since the tires will be slightly different overall diameter, which is definitely not good if the different in overall dimater is significant enough.

it is less important that you run the same tires all around, but as close to the same overall diameter all around.

Bump for more advice.

Another bump...anyone else?

dude, the guys above prety much explained it all. What more do you want to know?

^^ Just want more opinions/experiences with staggered wheel setups, including any negative impact it may have on the differential(s). I'm thinking since it's a IX, with the center differential in either a locked or unlocked position, it won't have the same overheating issues as it would were it a viscous coupling unit, but I'm wondering to what degree it may cause accelerated wear of the clutch packs in the ACD unit. Or maybe I'm totally missing some key concepts here since I'm just guessing on my part...

Everyone just explained it for you. Nothing will affect the center diff if you keep the same overall diameter as the stocker. You might get some odd wear because the tires will be stretched more on the wider wheels. Once again you will have no problems with the center diff if you keep the same overall diameter on all the tires. This has nothing to do with the width of the wheel or tire. Got it now?