Check this out first:
OffRoad TB - View topic - The Complete Lifts and Suspension Accessories Thread
And the "will it fit" tire sticky in the Offroad forum here:
Off-Road
Then we need to discuss the confusion about the term "spacers." Some folks use it to mean the disks that you put in the suspension to gain height (under or over the rear coil spring) or (inside or on top of the front strut). And it can also mean disks with threaded studs that you use to move the wheels and tires away from the center of the vehicle.
On our suspension design, especially the steering knuckle, the upper ball joint mount is EXCEEDINGLY close to the edge of the tire. If you want larger tires, above a certain size, you will need wheel spacers to obtain more clearance.
If you just want more ground clearance or to level the front without lifting the rear, you need suspension spacers of some amount to get the front to sit higher.
All depends on your intentions - appearance, offroading (mild or aggressive) or whatever.
No matter what you do, make sure the maintenance is up to date, especially the 50K fluid change interval on the transfer case.