In general, 16" tires cost more than 15" tires of overall equal size.
I own two 2000 Cherokees. My wife's is a Classic, with 16" wheels. Mine is a Sport, with 15" wheels. The Sport came with 225/75R15 tires, the Classic came with 225/70R16 tires. They are the same diameter. The difference in aspect ratio makes up for the larger rims.