Some 15's fit some don't on 2nd (3rd) gen Troopers. I ran 32x11.50x15's on my 2000 Trooper. 15x8 wheel with 4.5" backspacing. it worked great. I was running Centerline Hellcat wheels. The same ones on the blue Trooper in the Calmini catalog. They are no longer available. They were specially made to have the brake clearance of a 16" wheel. The problem is the rear brakes with the inner drum brake. That's makes for a bigger rotor and caliper combo than the fronts. The fronts have more swept area but the rear diameter including caliper is larger. I had about 1/4" clearance in the rear.
The above combo fit great. The tread was just covered by the factory flare and the sidewall stuck out just a little.