I searched on here and didn't find anything, maybe I'm stupid.

Anyway...
What is the lug pattern on the 90 suzuki sidekick?
and are there any rims that i should be able to find cheap that will fit on the sidekick to replace the stock rims that offer a ridiculous backspacing?

5x5.5" on all Suzuki 4x4's and their 2wd versions as far as I've ever seen.

Common swaps that I have seen are other Suzuki rims, Jeep CJ rims (but not anything after the '87 YJ Wrangler as they are all 5x4.5"), Ford F150 and Bronco rims (before 97 when they went to some goofy metric 5 lug pattern), Dodge half ton 4x4's (again, watch out for rims off the late 70's-early 80's when they used 5x4.5"), Kia Sportages from the 90's and early 00's, and a few others.  I know there's a post about this somewhere...

http://bbs.zuwharrie.com/content/topic,17635.0.html

http://wheeltool.com/info/5bolt.html#5-5%20    Note that this list is a little incomplete and the years are arranged backwards.

It is also important to note that the center hole needs to be big enough to fit the locking hubs.  I don't have the size at my fingertips, but a quick measuring of the center hole before rushing out to buy a set would be in order.  Junkyards are gagging on these wheels so you should be able to get a set cheap if you don't mind plain and used.

Just about any Samurai/Sidekick/Tracker will interchange in a pinch -- but the backspacing is different between the Sidekick/Tracker and the Samurai.

I run with early Ford Bronco (the full-sized truck) aftermarket wheels shod with 30" BFG A/T KOs on my Samurai.  I imagine that, with a mild suspension lift, I  could put them on my Tracker.

Hope this helps!

On my Tracker I'm running 15x8" rims off of a 60's Bronco that I got from the junkyard cheap...

the center hole needs to be more than 4 inches wide.
hope this helps. becareful if you are going to go looking for ford wheels as a lot of them are close but not quite big enough in the center hole.