I believe a 33x10.5 will fit (it'll be EXTREMELY tight though, you still might rub I would think), but you will rub if you go with the 33x12.50. Are you 15's or 16's?
If you go with the 33x12.50, you really want a wheel that is at least 8 inches wide.
35's though? No way.
Here is another thread on the subject.
2011 4x4 XLT on 33's stock?