wheel and tire question 18X9.5??

[uniquesnd]

So Thinking about doing 18X8 on the front and 18X9.5 on the back of my 86 regal what size drag radials would I need to run to keep from rubbing? I currently have hotchikss rear springs on the rear and competition engineering 3 way adjustables don't know if that info helps?

 

[gnon18s]

I have 285's on an 18x9.5" rim. I would say up to a 295 should work ok. (backspace on my rear wheels are 4.75)