If one side of the circuit fails, the other side is usually sufficient to stop a vehicle. Disc brakes,found on the front wheels of virtually every modern vehicle, are significantly more effective than the older drum braking systems, which can fade when hot. They still, however, need attention regularly. Underinflation, the most frequent cause of tire failure, is considered the main culprit in the recent Firestone tire-failure fatalities. Uneven or worn-out tires are the next most serious problem and can also lead to tire failure.
Uneven wear is caused by improperly balanced tires, or misaligned or broken suspensions.
Remember, all that keeps you connected to the roadway is your tires. If you don't check your own, have your mechanic check them every 5,000 miles. Your steering enables you to go around road obstacles and avoid potential accidents. Even a safe, well-trained driver is helpless in the event of a steering or suspension system failure. Such failures are catastrophic, especially at high speeds.