My friend has an 08 ext cab, 4x4, Silverado and just installed 33" tires and raised the front 2". Now he says it shakes when he brakes. Could the computer be learning the new set up and the ABS system trying to recalibrate or something? Anybody else heard of this? Thanks guys, he said he going to the stealer tomorrow but I hope to get him a better answer so they don't BS him. Thanks guys.