NO, especially if they are the ones that sold em to you!! We yanked off stock tires and rims all the time and replaced with larger ones.
Voiding warranties happens when you modify machines such as relocating radiators to top of the racks,etc. OPT

 

buy an 800 belt for it, much tougher belt, make sure your alighnment is alright while the cover is off, belt should be centered in both clutches

 

Well I decided just to get a new belt I'll change it tommoro and when I'm in the mud I'll use low gear.

 

So the tires should be fine then. I was goin to just put the stock tires back on

 

Just leave the tires on. We had guys that never had belt problems with big tires! OPT