What would be the advantages of larger wheels, for instance I could go to a 17" wheel on a SD vs. the stock 16's.

 

The advantage is look. I don't recomemnd it for a SD, though. Not too many tires made in 17" sizes that can handle the kinds of loads.

 

I can think of one major advantage, clearance. I mean clearance for the calipers and brakes or oversized pieces. Right now I have a stock F150 running 16x8 Baja's, and have no clearance to put weights to balance it out right. It took me a year of hassles to get someone to put wieghts on the inside and it's still not right. If I buy new 16" wheels it will either be casted different or I'll get 17's" and bay more for tires.