I would think the front axles would handle the additional weight just fine. My concern would be that you have the 3500 diesel so you can tow and when you put larger tires on the truck your effective gear ratio becomes higher (lower numerically) and that take power away form the truck.
I suppose it would take a little away. It does have plenty right now. I thought I would be towing a lot more with it, but that hasn't panned out. A 28ft bumper pull camp trailer and hay once a year has been about it.
