I believe they are pro comp series 98

 

Flip rim in the top photo over. Lay a yard stick across the rim after you flip it over looking at the inside. Measure down to the mounting surface from yard stick for back space. You get a more accurate measurement this way.
They looked like 8 wide inch rims maybe 8.5. Usually rims measurement is from the inside of the lip for width.
Some one knows more than I.

 

So I believe its a 17x8 4.25 bs Series 98 Rock Crawler - Gloss Black Monster Mod Wheel
picked them up. Just need to buy one more for spare. will chech backspacing tomorrow like you mentioned. wish they were 17x9 but i got a good deal on them from an older fello who never offroaded had winter tires mounted.

 

awesome! i love steelies!!

 

I think I have the spare you are looking for but I am in Southern California. I picked it up from a guy that had it for a spare but never used it. There is a 35" tire on it now so I am not sure of the width but it is a 17" and looks exactly like the picture.

 

I'm in Canada so it might be cheaper to get a new one instead of shipping, I don't need a tire just rim. If u decide to de mount tire and see if its also 8" and backspace I'd be interested