Here you go, Link!
http://www.puresuzuki.com/tire_chart.htmOr from the Calmini Site:
Suzuki Sidekick / Vitara / Geo Tracker
Equipped with 3" Suspension Lift System
Tire Size 30" x 9.5" Rim Size 15" x 7" / 15" x 8" Backspacing 3" - 3.5"
Equipped with 6" Combo Suspension System ( Suspension Plus Body Lift )
Tire Size 32" x 9.5" Rim Size 15" x 7" Backspacing 2" - 2.5"
These are the Maximum that Calmini Recommends - However, I found that with some Wheel / Rim Manufactures, 3 " or greater backspacing may contact the brake caliper. I have 3" backspacing with the Eaton Heavy-Duty Steel Wheels and had to grind a little of the caliper casting to get it to fit. Just something you should consider when choosing a wheel or rim, the way it's manufactured with the dish from the lugs to backspacing. (My Wheels are 15" x 8" with 3" Backspacing and 32" x 10.5" TSL Swamper Radials. If I had to do it again, I'd go with 30" or 31"tires with a wider tread width on these rims. Oh, and I have the Calmini 3"+3" or 6" Suspension Combo lift. FYI)