Researched a few threads - this is a slight variation on a common theme:

Champion RG5 Rims:
18x8.5 Front (0.5 wider than stock)
18x11.5 Rear (0.5 wider than stock)

Current Tires are stock size PS2s:
225x40x18 Front - Barely worn
295x30x18 Rear - Worn out (corded on inside rib)

I need new rears:
Looking at PS2 315x30x18 since the 295s were a bit "stretched" on the 11.5 rims.

Here is the Question - All specs based on Tire Rack tables for Michelin PS2s
225x40x18 spec out:
25.1" diam & 829 revs/mile (measured on 8" rim)

315x30x18 spec out:
25.5" diam & 817 revs/mile (measured on 11" rim)

My calculations say 817 is 98.5% of 829
Both actual rims are 0.5 over measured rim

Good Enough to avoid AWD related issues????

 

I have 315/30/18 and 235/40/18...MPSC. No issues at all!

 

go with 235/40-18 front if u can. on the 8.5'' wide that is.