'69 Barracuda w/ spring reloc, max rim/tire width? AdamR??? Anyone??

First, Nice fish !

Im running a 15X8.5" centerline auto drag with 4-7/8" backspacing. My rims are still small bolt patern.

Since you have a Big bolt patern you can go a little deep on the back spacing. 5" is probably the max back spacing you can take.
In the stock wheel well with the 5" backspacing a 9" rim will probably be as wide as you want to go.

For tires I'm running a 275-60-15 right now. They are 28" tall with a 11.5" section width and a 9" tread width.



Before these I was running a Hossier quick time 325-50-15. They are 27." tall with a 13.2" tread width and a 11" tread width. They just fit in the wheel well but would rub around corners. If a used a radial instead of a bias ply they may not have rubbed. They are however to wide in my opinion for a 8.5" rim. They really need a 10" rim.





If you plan on leaving the wheel wells alone I would stick with a tire no wider then a 12"-12.5" section width and around 28" tall. Most people say 28" tall is max before you get to close to the front of the 1/4 panel but I have plenty of room and could probably get a 29" tire but my car sit pretty high right now and that will probably change when I lower the rear a bit.