So it look very likely i'll have to use a spacer to allow my front wheels to clear my new brake setup. I'm wondering if I go with the H&R 15mm spacers in the front (do they make a 10 or 12?), should I do the same in the rear, leave it as it is, or go with a smaller spacer, say a 5mm? I'm trying to get the smallest spacer possible for the front so that the brakes will fit under, but I'm slowly coming to the conclusion that it's probably going to have to be 10mm or bigger.

 

I would suggest that you leave the rear alone if they don't need it. Also, like you said, use the smallest you can get away with. I ran 5mm spacers on the ITR for tire clearance and I was very happy with the H&R quality. Big spacers (15mm+) can add stress to your hub/bearing assembly. Could you fix it with wheels?

 

with the 5mm H&R spacer did you have to get longer wheel studs? and where can i order a pair of these spacers.?

 

Nope, stock studs. I mounted them for the first time with an open ended nuts to make sure I was getting enough bite. This was with OEM wheels. Other wheels may give different results.

 

15mm is a lot!
you will definitely need longer studs. What brake convertion are you doing that requires that big a spacer?
I think you should instead lok into getting a set of wheels that fit over the bigger rotors, as already stated you WILL wear out your bearings a lot faster with a 15mm spacer.