New Wheels - back spacing? offset? IDK

I'm currently running 31x10.50x15's on my stock 1990 XJ Limited wheels (15" x 7" I think). I am going to switch to 33x12.50x15's - or maybe even 35's - and I know my stock wheels are too narrow. I also want my tires to stick out farther (wider stance) and I don't want to run spacers.

What should I look for in a new wheel? Back-spacing? Offset? I have no idea what the difference is or what I would even ask for...

offset is usually used on fwd or sport compact car wheels... you want something with a 3.75"ish backspacing, maybe 4".

A good cheap option is the Cragar 15x8 wheels with a 4" backspacing. Can be used with the 33's or the 35's.

http://www.summitracing.com/parts/CRR-3975812/