does the tire balloon out to extremes at all? if so would that effect response greatly? anyone have a pic of a 255 on a 8.5" wheel (such as oem)

 

They are only 1/3" wider than the 245/40R17. It is not really going to ballon. You are looking at 1/2 of the 1/3" on the inside of the tire and 1/2 on the outside. It is just a little bit wider and they do look a little meatier.

 

not to extremes. The BBS wheels I have are 8.5 in the rear. Same as OEM.