i have found some 15 inch aluminum alloys one said 15x7 jj then the number 8 and then says 8 inch offset.the second said 15x7 jj then the number 10 but no mention of any kind of offset.these were on a `91 fourunner in a junk yard,they are six lug.my question is are all 15`s the same or were there differances,offsets,etc.my `86 4x4 has 14" factory alloys.

 

No way that rim could have an 8" offset (that would have the mounting flange sticking 4.5" out beyond the inner face of the wheel) maybe it is 8mm. You can easily measure the backspacing and check if they are the same or not:
- http://www.4crawler.com/4x4/CheapTri...ne_Pix/24.html



Offset and backspacing explained:
- http://www.4crawler.com/Diesel/Tires.shtml#WHEELS

 

probably 8 and 10mm offset.