If I'm rolling along in a AD 1/2-ton at say 30 mph, and I hit the emergency brake hard, should properly adjusted brakes lock up and skid the rear tires or just slow me to a stop? For me, it's a moderately fast stop but not a skid. I'm wondering if this is normal or if my brakes need adjustments. The thought of using my brakes in a true emergency is a bit unsettling.