Crager soft 8 Questions

Ok I am in the market to get some crager soft 8's for my limited 1999 awd ex. I am looking to put Hankook Dynapro atm in a 31x10.50x15 on them. My ex is not lifted and I am looking to get it that nice flush stance with the fenders. I have a few questions though.
1. What would be a better size 15x10, or 15x8
2. What bolt pattern and rear spacing would be best.

Thanks.

 

[Trac726]

If your going with a 31X10.50 your gonna want the 15X8. Im not sure as far as back spacing goes.

 

[MidnightRebel07]

15x8 with 4" backspacing, I have these wheels on my lifted '03 Sport Trac 4wd XLT. Got them cheap from Summit Racing...

 

[MidnightRebel07]

I have 33x12.50x15 DuraTrac's just so you know.

 

[skia4life89]

I have 33x12.50x15 DuraTrac's just so you know.

Thanks for the info, and a newb question I know, but what exactly is Backspacing, and what does the different sizes mean?

 

[MidnightRebel07]

This link will teach you everything you need to know about wheel/tire info.

http://www.rimsntires.com/specs.jsp