I ( for the whole winter) have been experiencing a problem, i think in the rear brakes on my truck. when i come to a stop sign or try to stop and its even remotely slick out my front brakes pulsate ( as they should) but right through the stop sign and further if i let them. it doesnt feel like the back brakes are even working. I took the rear tires off and they are engaging when jacked up and i also just was told my wheel bearings ( one or both front) coulod be causing this?? Any ideas?? thanks alot