But don't I need to know which lift I'm getting so that I know how big the tires could be?
It's a give/take relationship. Why not run the new 49" IROC's on the Tracker? They are the biggest DOT tire. Well, give that it's not going to happen for a lot of reasons, take that it will never happen for same or different reasons. You have to weigh which fits your driving type, style, terrain and funds.
Have you priced tires for tire sizes you are interested in?
I have a friend with a Jeep lifted 3.5" on 31" slick's. His stock gears are 3.08s. It's a YJ with an EFI 6 cyl, yet he has a set of 4cyl YJ axles, which come with 4.10s stock. He's debating on 33's or 35's tires. Either way, he has to regear or swap axles. He hasn't made up his mind though. Now, either tire will break that puny D35 easily with the right foot on the pedal. So does he put money into the D35 with the stock 4.10's, or does he upgrade with a 8.8 Explorer rear axle (he has one with 3.08s) which has to get regeared. If you get regeared, you should lock it also to keep the costs of installation minimal. To add a locker case, you have to re-install the gears, not just install them.
Cost for tires range upwards of $90 difference per tire same brand. Then there are other impacts of running a larger tire on the Jeep he is considering also, longer shocks, slip yoke eliminator/2-pc driveshaft, longer brake lines, resealing the axles, redoing the brakes, among other little stuff, ie studs.
So compare what you can run with what size tire for what terrain you'll be driving. Then evaluate the impact on the drivetrain.
You can do baby steps in these types of vehicles. It's the best thing which I think is the best thing. Add spacers, add slightly larger more aggressive tires, evaluate other areas to mod ie. shocks, struts, brake lines, parking brake line, gears, lockers, skid plates, bumpers, winch, roll cage, etc.
Then take the next step.