You’re driving down the block and a bike rider appears from a side street. As your vehicle slows down, you notice an unsettling vibration in the steering wheel. Lately, you’ve also noticed the vibration anytime you use the brakes.

Your first instinct tells you something has gone wrong with the tires, but a new set was installed a couple months ago.

“The problem could be caused by a worn or warped rotor,” said Tony Molla, vice president of communications at ASE. “Warping can affect the ability of your car to stop, especially at high speeds.”

Brake pads push against the disc-shaped rotor to stop your vehicle. Heat builds up as the brake pads make contact with the disc and heavy braking can cause uneven wear. For instance, constant use of brakes as you drive down a steep mountain road can cause a warped disc.

Worn out brake pads can damage a rotor by creating small grooves like a phonograph record. Regular brake maintenance can help extend the life of your car's rotor.

“Those warps and grooves translate into vibration in the steering and brake pedal,” Molla said. “Rotors are an essential part of the braking system and should be inspected at least once a year.”

Vibration caused by rotors can interfere with anti-lock braking systems found on most modern vehicles. ABS assists drivers when making sudden stops and helps prevent skidding.

“Today, rotors are designed to be replaced rather than repaired,” Molla said. “It’s usually easier, faster and safer.”

Here are some of the common problems that lead to rotor replacement:

• Aggressive braking. Stomping on brakes can accelerate wear and place sudden stress on one part of the rotor.
• Over-tightening of wheel lug nuts. Applying too much torque can create small impressions or “dents” on the rotor.
• Mountain driving, especially in hot weather and when pulling a trailer. Friction builds up and can cause rotors to become warped.
• City and freeway rush hour driving. Constant braking builds up heat and increases rotor wear.
• Worn out brake pads. The metal surface of a worn out pad can cause grooves on the rotor.

“Rotors are an essential part of your braking system, “ Molla said. “Fall is one of the best times to have them inspected after a summer of driving on hot crowded freeways and mountain roads.”