Best tire size for the rear would be a 305/30/20 but not too many companies make it.
Toyo T1R has it....It's the perfect height at 27.2" and should look ok on a 10" wheel and better on a 11"
+1
that 315/25 would be too short
Are you running the R888 in the 305/30/20??
How do you like it? How many miles are expected with normal driving?
Thanks!