I'm getting spacers for my TJ to run the 35" KM2s on the 7" wide/3.75"BS wheels. I have less than my thumb thickness between the tire and rear coil bracket. I've received only 2 of the 5 tires and had them mounted so far. They are on the rear axle.
I was told by everyone I talked to who sells them or runs them not to add loctite on the nuts. You are to torque them properly with a torque wrench. Then recheck after 100 miles, 500 miles and 1000 miles to verify the torque on the nuts. All this is due to the forces that come from the torque arm geometry of the spacer itself with the tire/wheel and axle.
I should be receiving my other 3 tires tomorrow and hopefully will receive my spacers from Cali by Friday. I've got wheeling plans for this and next Sats.
As for your delima to fit the correct wheel to match with the tires to go on the TJ or to use the spacers, yes, spacers will push the tire outside more as well as give you a wider track. This will give you better handling on the vehicle, but it still won't make it a corner handler so behave/drive correctly. To provide the necessary clearance, cheap way is to use the other model original springs. Next would be the polyurethane spacers, and last aftermarket lift springs. Next concern would be shock options. Then track bars.
You may be able to use your stock shocks with the other model springs (like a LJ Rubicon or even a set of new JKs). I've gained more than an 1" of lift using 05 Rubi LJ coils on my TJ. (I also have 2" spacers and 1" body lift for my combined lift.) I heard JK springs provide 1.5+". I picked up a set of JKs from the local Jeep dealership (off Ebay) for $5. This also included the shocks. They did a lift kit before they sold the JK.
Poly spacers are good as well as cheap to gain lift or separation between axle and frame. Many are sold as kits to include shocks, spacers, and rear track bar riser. Many are sold just as spacers. Teraflex just had a 24hr sale on their 2" spacers that were blemished. They had some flaw that was more cosmetic than anything else and they didn't pass their mfr inspection. I picked up a set of 4 delivered to my house for under $30. Check their website (teraflx.com) as they have other blemished products (diff covers).
Last option are lift coils. There are some companies that provide a 2" lift coil and sell them cheaply as well. They could come as a kit to include shocks. Rough Country has such a kit.
Check it out]=http://www.4x4rockshop.com/Scripts/prodView.asp?idproduct=13820]Check it out. There is a discussion going on
here about it.
The rear shocks have tendency to contact the coil mount bracket on the axle during full extension when trailriding. There are shock offset adapters that push the shock enough off the shock mount to clear the coil mount.
Best thing, you should use new shocks as well as get an alignment on the front axle no matter which way you go. Do note, the more you separate the axle from the frame, the more the axles won't be centered under the frame. The axles are located with control arms front to rear and track bars side to side. Many kits include shocks as well as a rear track bar riser for the rear axle. There will be instructions to tell you to drill a new hole 3/4" off and use that to locate the front track bar and 'recenter' the front axle. Since the front track bar has a tie rod end, it may be needing replacement or in time with the increase angle with the lift, it will require replacement. Its not really critical usually since many jeepers just add the spacer lift and new shocks to run 31-32's and they will accept the axle misalignment. Replacement track bars are readily available from a dealer, but adjustable length track bars provide less binding on the suspension during cycling. For a mostly street seen TJ, redrilling is acceptable up front.
Depending on where you live, check your local Jeep club and the Craigslist for someone selling items which you could use. Many Jeepers are continuously 'upgrading' what they have.
As for the newer wheels/tires,
here is a discussion of someone doing just what you want to do.
Lastly, with your newly Jeep, look for a local club to join and enjoy as well with your Jeep on trailrides.