With the SP1's you can run a HUGE lip and Low offset in 19's or 20's. 19 x 11 is very doable and so is 19 x 12...
Here are a couple of offset options for you:
F:19 x 9.5 MD+10
F:19 x 10 MD+16
R:19 x 10.5 SL+5
R:19 x 11 SL+11
R:19 x 11.5 SL+18
R:19 x 12 SL+24
These offsets should fit just Fine giving you the biggest lip possible on the biggest rim possible.
GL