I have a 98 z28 it sits an inch higher in the rear, is this normal? anyone know stock road height measurements front and rear? whats the widest tire to fit without suspension work

 

Not normal. You can get stock body measurements from the factory manual. You can download a copy of the manual here:

LINK: 4TH GEN SERVICE MANUALS; 82-02 PARTS DIAG; 99-02 WIRING DIAG - Firebird Nation

Many of us run 315/35-17's in the rear, on 17 x 11.0" 50mm offset wheels. Minor hammering or trimming the jounce bumper brackets may be required. No suspension modifications. There is a "sticky" on the Wheels and Tires forum with complete details.