i'm happy with the 31's on 7", but don't know back space- aftermarket jeepcj wheels.
i tried some 8" w/31's, but they rubbed more than i wanted to modify w/hammer(modify happened anyway).
i did a minor bodylift am refining/adding skid protection.
i think some rectangle tube before my rocker panel mashes into my door...

Just bumping this up to address my question about going 30's or 31's with my tracker.

*EDIT* sorry but I forgot to ask, what is the bolt pattern for these trackers/sidekicks?

5 on 5.5 for the tires. I'm not sure about the back spacing for 31's though on a Tracker.  As for getting them to fit, I know a few people are running them with the 2" spacer and 2" body lift.

ok cool...5 on 5.5. Sorry for all my ignorance on this stuff, Im just used to full-sized trucks and kinda new to the technical part of this rigs.

Im pretty sure that 31's will fit with the setup I want to run...Im just worried about the power loss mainly. Kinda want others input as to stick with 30's to keep my power or go 31's/deal with the power loss 

I have gone your route so let me save you some money.     Get the spacers.  1.5" in front and 2" in the rear.  31" will fit with some fender trimming and hammering.  I had 31" x 10.5" super swamper tsl's on 15x8 crawler rims with 3.75" backspacing (which will not rub lock to lock).  These will work fine on the road.  You will lose 5th gear in a head wind and be noticable slower off the line.  There is a lot of tire and rubber there and it takes good grunt to get going (even with a header which if your going 31's you should add to your list).  Here is the big problem.  My 31's tear into my fender wells when you compress them up.  You would have to increase your bump stop to keep this from happening.  They also stick out so you will need fender flares to be legal for onroad. 

I have since dropped that project for a samurai which I have switched the tires to.  The sidekick/tracker is a great platform and if I wasn't knee deep in this sammy I would have continued with it.  Step one would be if you are doing just spacers to not go 31" tires.  You can get TSL in a 29" tire by 8.5 which can fit on the stock wheel.  This is important because the stock rims are MUCH lighter weight than steel wheels.  I think best bang for the buck on the cheap would be the 29" tsl's, stock rims, Jeff's spacers, doug thorley header (optional but it does make a difference with a good exhaust), crown vic shocks in the rear, stock struts front with the mount flipped in the front.    I love my kick which is why I keep it as a seconday daily driver and it runs 235's on the street.  Oh yeah, and ditch the front sway bar.  You'll get much better flex and you will notice only a little dive going into a high speed turn but honestly I drive mine like a go cart and never had any scary moments.   
 

I kinda figured that the power loss when stepping to 31's on steelies would be enough to notice...just didn't know how bad. Are there any decent Aluminum Wheels out there that you guys are running? Seems like most have steelies...

Thanks for all your help! It looks like I will stick to the original plan on running 30's

I chnaged my ally rims for steels. Steel rims are more robust and in a lot of cases lighter than ally rims. Ally is 1/3 the weight of steel but ally rims for 4x4s tend to have much more metal then steels.

I kinda figured that the power loss when stepping to 31's on steelies would be enough to notice...just didn't know how bad.

Real bad. Unless you live in a flat area - stick with 29" tires. Your gas mileage will go to crap, acceleration will be non-existent, going uphill with camping gear will put you in 3rd or 4th gear on the highway, way added stress to the driveline, breaking distance will increase by about 50%, and your low crawl ratio won't be very low anymore.

29" tires on stock wheels is cheap ($550 ish). The money you save will pay for lockers ($500) and spacer lift ($300) - which will do you more good than the 31" tires. I'd also consider the OME lift ($750) if you can afford it (if you can afford 31" tires, you can afford the OME lift). I think the tracker is superior to the samurai in every way, but it's Achilies heel is gearing options.

If you want a serous wheeling monster & want to be able to drive on the street, get a Kicker 3 (search) - but that's expensive and a whole new ball of wax.

Are there any decent Aluminum Wheels out there that you guys are running? Seems like most have steelies...

The #1 failure on trails is tires (popping a bead, poking a hole in the tire, or bending a wheel on a rock / tree). If you bend a steel wheel on the edge, you can beat it back with a hammer / rock. With aluminum wheels - you're stuck.