235/75's are about it for stock.  Even then you might run into some problems with the part just inside the wheel well interfering.  What I'd recommend is getting one mounted as your spare taking it home and mounting it in the driveway, then checking clearance by turning the wheels lock to lock.  If there's a spot that's close, leave the wheel there and jump up and down on the bumper to make sure it'll clear throughout the suspension's travel. Calmini has a chart on their webpage that shows what tire sizes can fit with stock, body lift, suspension lift etc.
http://www.puresuzuki.com/tire_chart.htmThe rear shouldn't have any clearance problems with 235's though. ÂÂ
If you want to go any bigger you're going to have to lift it.  I just put 31x10.50 Dunlop Mud Rovers on my 2 door over the weekend and even with the Calmini 3" body lift I had to do a little bit of artful work with the sawzall and a hammer inside the wheel well in front of the door since for some dumb reason the factory design has about 2 inches of sheetmetal that enclose a bunch of empty space that sticks into the wheel well.  On the upside I didn't have to touch any of the outer fender so unless you look into the wheel well it still looks unmodified.  (I probably should get to putting up a damn website for all my car stuff one of these days I guess).  The 31's fit ok unmodified until you turn the wheel a little bit then they run into the bodywork that sticks out into the wheel well.  The rears didn't need any modification for the 31's with the body lift on there already. I'm also not running a back bumper, I think the pretend factory mud flaps might be in the way if they were still there.  I'm not using the recommended 2.5" backspace rims though, mine are more like 3.5" backspace on 15x7's.  With 2.5" backspacing, the problem of the edge of the tire hitting the bodywork up front will actually be increased slightly, possibly to the point of requiring cutting away visible parts of the fender.  No biggie just something to be prepared for if you go that route.
The 31's definitely look nice though, I had 235/75's on there before and the 31's are about right looking with only the 3" body lift.  Heck my wife even thought they looked better and she's not a car/truck person so that's gotta be saying something. ÂÂ
I honestly think for the 150 or so to buy it the 3" body lift is worth it.  A lot of people here say it's hard to install but I thought it was pretty easy all in all.  If you've got an automatic the only nuisance to doing it is the t-case shifter extension and bending the shifter lever, I didn't even bend mine, I just cut out a little bit of the sheetmetal in the hump and slid the whole boot back a few inches instead.  I'm not running my rear bumper as a result of that but after looking at the design of the stock bumper core, I don't think it's gonna make much difference in a wreck anyway honestly.  I also am just running the core of the front one now instead of the urethane cover since I didn't feel like welding the steel plates to move it up on there.  Installing it this way isn't maintaining a factory appearance obviously, so if that's a concern yes the body lift is going to be a bit more work.  If you don't care though it only took me about 3 hours to put the lift on using a hydraulic floor jack and some 2x4's.  You will have to weld some small spacers onto the frame afterwards, I'm lucky to have a buddy with a nice MIG welder so this wasn't an issue.  Even if you don't I can't imagine a shop charging more than 20 or 30 bucks to tack the spacers on there for you though.  As it is I still have a gap between the cab and the spacers that hasn't ever touched as far as I can tell which tells me the spacers might not be all that necessary but if you have passengers in your 4 door regularly I wouldn't recommend leaving em out. ÂÂ
Anyway sorry bout the info overkill there, kills time for me at work nicely though.
