Can I put wheel spacers on the rear of my 90' F150 and not worry about it? Or should I not do it for any reason..

 

what thickness were you thinking about?

 

I'm not sure. I just noticed my fronts are more even with the fenders and the rears are tucked a little too much for my taste. I was just sorta wondering what my options were. I don't know what's out there.. 1 inch? More? Is that possible with stock studs? Should I be upgrading that too..

 

They go up to 3" thick, but I don't think its a real good idea to use them. If you have stock tires and don't abuse the truck or haul any weight in it you probably could get away with a spacer that big without a problem. I still don't think its a good idea though. It basically has the same effect on the axle (and balljoints/bearings in the case of front wheels ) as a wheel with a big offset.
Now with something like a 1" spacer you should be safe because its not much of a difference. Just like going to a new wheel with 1" more backspacing.....usually not a problem.

The spacer bolts on to the stock studs with special nuts, and then the wheel bolts on to the spacer with a new set of studs that are centered between the stock studs. So yes, your stock lug nuts are fine, however with thinner spacers you might have to get the sawzall out to shorten the studs if they hit the wheel.
http://www.marlincrawler.com/htm/axles.htm#spacers Scroll down to the bottom, good picture