A car is driven over a curb twiceonce very slowly and once q

A car is driven over a curb twice—once very slowly and once quite rapidly. What would you need to know about the car in the second case that you did not need to know in the rst case if you were required to nd the tire force that resulted from going over the curb?

Solution

I hear this from customers all the time; they pull into the garage and say, \"I need to have an alignment on my car because my steering wheel shakes when I drive on the highway.\"

The truth is an alignment has nothing to do with your car shaking or your steering wheel vibrating. If you tell your mechanic you need an alignment, and they don\'t ask why, find a new mechanic. A good mechanic will always ask why you need work done on your car, so they can get enough information to decide how to fix the problem on the first visit.

Alignment, Balance: Two Different Things

Mechanics use these words to refer to different operations, though sometimes you get them both done at once.

Alignments only realign the tires so they are all pointing in the proper direction while driving down the road. If a car’s tires need alignment, it may pull one way or the other instead of straight when you let go of the steering wheel, or the tires may wear unevenly (deeper on the inside than the outside or vice versa).

If a car\'s tires need balancing, on the other hand, it may shake at freeway speed, or the tires may wear in a cupped or scallopped pattern. Balancing a tire means making sure the weight of the tire-and-wheel unit is balanced all around the axle, with every section having equal weight. The first step in balancing a tire is to match the heaviest part of the rim (usually the valve stem) to the lightest part of the rim (a yellow dot painted by the manufacturer on the tire\'s sidewall). Then the mechanic places the tire and rim on a balance machine, which positions plastic or metal weights as needed on the outer part of the rim to fine-tune the balance.

Balancing is something you might do routinely whenever you rotate the tires, every six months or 6000 to 7500 miles. Sometimes tire stores will offer you lifetime tire balancing and rotation. I highly recommend this service. Checking the tires routinely to see if they are wearing oddly will make them last longer and cost you less in the long run.

Alignment is something you might do routinely every year or so. It won\'t stop a steering wheel vibration, but it\'s good preventative maintenance, especially if you drive often on potholed, cracked, or dirt roads.