What kind of backspace and offset do I need to clear ITR brakes? These will be used for slicks so I am not real worried how far they stick out past the fenders(within reason)

 

I was able to get a 15x8, +35mm offset Rota RB wheel to clear the ITR caliper in front. That's 5.38" back space. It would also be the equivalent of 5" back spacing + a 10mm spacer.

It depends on the wheel, but I'd say 5" back space with either a 5mm or 10mm spacer would do it. I'm not sure if they can make them in half sizes too.

I just ordered my 15x8 Spin Werkes with 5" back spacing, and I have a couple of 5mm spacers I can use for test fitting.

 

15x8 +35 Rota RB?

Is that a 4x114, or 5x114 bolt pattern you are referring to?

 

4x100