Q: I’ve noticed a vibration at times while driving on the freeway. A friend in another car observed that my front tire was intermittently bouncing like a basketball. It would stop after a short period and then start up again farther down the road. Is this something dangerous? What do you think is causing this?
A: This could very well be considered dangerous. If the vehicle tires are not staying in constant contact with the road, your control of the vehicle is seriously compromised.
The most likely cause of the bouncing tires is worn-out or broken shock absorbers. Unfortunately, shock absorbers are one of the most overlooked wear items on vehicles. The shock absorbers are the next most important safety items after your brake system. They are there not just for a more comfortable ride, but also serve to control the suspension movement so that you, the driver, are able to control your vehicle when braking or steering.
Shocks in need of replacement can result in the following.
• Body roll (side-to-side movement), which adversely impacts handling and control.
• Loss of traction, which increases stopping distance and negatively affects control and acceleration.
• Tire cupping/uneven tire wear, which shortens the life and performance of the tires and can cause road noise.
• Nosedive when brakes are applied, increasing stopping distance, negatively affecting control and resulting in premature front-brake wear.
• Bottoming out going over bumps, which negatively affects vehicle handling and control, resulting in premature wear of the suspension components.
• Acceleration squat (the rear of the vehicle drops upon acceleration), which adversely affects traction, vehicle handling and control.
In most cases, by the time a vehicle has gone 50,000-60,000 miles, the shocks (shock absorbers/shock struts) have deteriorated to the point that new shocks will have a noticeable, positive effect on your vehicle’s ride and control.
This wear on your shocks happens so gradually that you may not notice until they are so worn that your vehicle is dangerous to drive. Approximately 80 percent of vehicles in the wrecking yards still have their original shocks, and most were candidates for replacement at least once. Based on your description of vibrations and bouncing tires, I advise you to have your shocks inspected by a shop you trust as soon as possible.