What backspacing i need with aftermarket 15x8 wheels

[Slow5.0]

I going to buy two aftermarket 15x8 or 15x9 wheels, i was wandering what backspacing/offset i need to fit on my Stang with 26x10.5-15 M/T ETs

 

[legalize420]

dont know about 15x9 but 15x8-5.5" and 15x10-6.5"

 

[JOEGTS]

I have 15x8 with 5 1/2 backspacing and 275/50/15 drag radials. If i had it to do all over again I would have went with 15x10 with 6 1/5 inch backspacing, they look better.

 

[Slow5.0]

I have 15x8 with 5 1/2 backspacing and 275/50/15 drag radials. If i had it to do all over again I would have went with 15x10 with 6 1/5 inch backspacing, they look better.

Do you have any pics of your rear tires/wheels

 

[JOEGTS]

I am to computer challenged to post them.