if you have a 03 1500, I know for a fact you can run 35x12.5x 17 or 20 on stock rims with a rough country lift,
If you look at Fabtech .. they say you need aftermarket rims.
I dont remember what BDS, Skyjacker or Rancho where because it has been a while since I researched the lifts for our truck but when in doubt email the manufacture of the lift and they can tell you exactly what you need to know.
I'm running my stock 20's with the fabtech lift. There's not much room to the spindle from the widest part of the sidewall, about 1/2". Tires flex at the contact patch so this isn't a problem, unless I wanted to run wider 20" tires -which I don't. 17" wheels are my wheel of choice anyway so this doesn't matter much to me.