I would appreciate any input and ideas before I start troubleshooting tomorrow afternoon: I just recently put some larger tires on the truck, from 31x10.50 AT's to 32x11.50 mud rover's. My brakes have since disappeared, before I put the new tires on they were getting a little spongy (if that's a correct term). But today I had to stop from 60 MPH and it took me well over 200 yards to do so with the pedal to the floor (ended up having to downshift the tranny to help stop it). The Brake idiot light is on constantly now, I have fluid in my master cylinder (although it's kind of black looking). The rubber part of the brake lines don't expand when the pedal is pressed. The past few weeks both the discs and the drum brakes have been squealing rather loudly as well. This is on an 87 K5, 350 TBI / 700R4 (vaccuum brake booster I believe), and if it makes any difference, the 350 has a Comp Cam 270H running in it with stock ratio rockers. My current ideas are; check the vaccuum lines, and brake lines for leaks and inspect my pads/drums/rotors. Anything to do with the master cylinder or booster I really have no clue about. Brakes really aren't my forte, so once again, any input would be greatly appreciated.