Welcome to the site. The biggest tire you can fit on a non-ZR2 blazer is 30x9.5x15 depending on the tread design. The torsion bars may need to be tweeked a bit depending on the truck.
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2000 Chevy Blazer ZR2
Performance Mods: Numerous
Suspension Mods: Some, but not enough
Exterior Mods: Just Right
1987 Buick Turbo T Dark Red
Low 11 sec sleeper
.030 4.1 block, PT6262E, & other odds and ends....
My Cardomain