can any one tell me the largest rotor i can run with baer brakes and stock 84 Z28 15" rims??

 

Baer's website gives wheel size info for each of their product offereings. The SS front setup may fit in your 15's- if they are aftermarket. The only way to be sure is to download Baers fitment template- also available on the their site. Watch the scale on the side of the template to be sure it is real-size.
S-D

 

"SS Serious Street
Baer's entry-level system. Offering weight savings in addition to dramatic performance enhancements over most OE muscle car brake systems, "SS" system are popular for cars that run on both the street and the strip. SS systems feature a 11" diameter x .810" directionally ventilated rotor and 2 piston PBR DOT legal aluminum calipers. SS packages can be used with many aftermarket 15" and most 16" wheels."

Heck, if you know you gotta get new wheels for the brake upgrade get the Track setup and go with 16" or 17" wheels.

 

actually my snow tires are on 15 inch stock wheels, don't want to spend another 300 bucks plus wheels