They will rub. I have 2 inch leveling kit and 285 65 20, on the stock 20" wheels. this translates to about 34.5 x 12, using a tire size converter calc. I installed a 2 inch wheel spacer mine rub slightly on the plastic wheel well liner when I turn hard left.

 

You have a 2" wheel spacer?!?!? All you need is 1/4" and they shouldn't rub at all...

 

I'm going through this right now and I can't get a straight answer either. I bought a RC 4" kit that suggested 1/4" spacers to run 35x12.50xR20's on the stock wheels, but the shop guy said I'd need at least a 1" spacer - so I ended up buying 4 new rims with more backspacing.

If anybody's in the market for a set of chrome-clad 20"s with Goodyear Wrangler HP's (12k miles) or a pair of never used 1/4" spacers PM me...