They look amazing buddy. I'm so in love with your E92, is that bad?
Current Specs are:
F. 18x10 et25
R. 18x11 et25
F. 275/35/18 Rivals
R. 295/35/18 Rivals
Correct?
The Rivals do not come in a 285/35/18, so you would have to run an RS-3 or PSS to get that size. The RS-3 & PSS run more true to size, whereas the Rivals run pretty wide to your avg street tire. The 285/35/18 RS-3 or PSS in combination with a slightly smaller spacer (8mm) should do the trick.
The only downside is you will have mis-matching tires for a while. But, when the front Rivals wear out, you can replace them with 275/35/18 RS-3 or PSS so you have a matching set again.
EDIT: You are going with the PSS I see
