I would get 8.5 and 9.5 or 8.5 and 10. 8 and 10 is too big of a difference, the front is going to have the tire hanging off the rim and the back is going to be stretched because its too thin for a 10". I have looked at this for a while and have had many wheels like HRE, DPE and IF, also have done the math.
I'm looking at getting 19x8 front with 235/35/19 and the 19x9.5 with 275/30/19
The tires will have the same look on the rims and same 82mm profile.
E90 335iA BLK/BLK 19" IForged Daytona, UR Intake, JB3 2.0, RR DP, AA intercooler, HKS BOV, KW C/O Street Comfort, 424whp