Doing the Straight & Narrow
Proper wheel alignment improves your car's handling -- and
helps increase the mileage you get out of your tires
by Peter D. duPre
Have you ever noticed that your vehicle will often start pulling to one side
after youve rolled over a couple of potholes? Hitting a pothole, even at speeds
as low as 25 mph, can knock your wheels out of alignment. When that happens,
your ability to control the direction of the vehicle may be compromised; the
tires will also wear rapidly and unevenly. Additionally, your vehicle may be
difficult to keep under control. To get back that control and increase the life
of your tires, you need to have the wheels aligned.
A wheel alignment normally requires adjusting the relationship between the suspension/steering
components, wheels and the frame of the vehicle. An alignment makes sure that
all the wheels are parallel with one another and that the tires meet the road
at the correct angle. Every car manufacturer has a set of recommended alignment
specifications for each model they build and every vehicle is properly aligned
when it comes from the factory so that it tracks straight, steers easily and
maintains even tire wear (as long as correct air pressure is maintained). As
the vehicle receives wear and tear, a periodic realignment of the wheels is
necessary to return the vehicle to this factory specification.
So how do you know if you need an alignment? Simple, just pay attention to
a few warning signs:
- Look for unusual tire wear. Check all four tires. If one or more
of them shows excessive wear on one side of the tread or wear in a cupped,
scalloped, a diagonal stripe pattern across the tread, or feathered edges
on the treads, an alignment is probably needed (along with shocks or struts).
- Unusual steering. If the vehicle steers "stiffer," or does
not return to the center position when released, you may need an alignment.
- Cocked steering wheel. If the steering wheel is not centered when
the vehicle is parked with the wheels pointing straight ahead, you almost
certainly need an alignment.
- Crab walk. If you notice that your vehicle wants to move "crab-like"
down the highway, that is, with the rear end cocked off to one side while
you are driving straight, you need an alignment immediately.
- Pulls to one side. If your vehicle noticeably pulls to one side you
may need an alignment. Before you rush off to the front-end shop, however,
check to make sure your tires are properly inflated. A vehicle, which has
one of the front tires over inflated or under inflated, may noticeably pull
to one side. Once the tire pressures have been adjusted, if the vehicle still
pulls, an alignment will be necessary.
So just what does a front-end technician adjust during an alignment? There
are three basic wheel angles that determine alignment: camber, castor and toe-in.
Not every angle applies to every vehicle and not all angles are adjustable on
all vehicles, but the three angles together, must be within specification for
a vehicle to be in proper alignment:
- Camber is the inward or outward tilt of a wheel compared to a vertical
- Castor is the degree that the vehicle's steering axis is tilted forward
or back from vertical as viewed from the side of the vehicle.
- Toe refers to the directions in which two wheels point. Toe-in means
a vehicles wheels point toward each other or look pigeon-toed. Toe-out means
that the wheels are pointing away from each other. Too much of either is not
good; it can make steering difficult and severely increase tire wear. Back
in the days when all vehicles were rear-wheel drive, it was generally necessary
to adjust the alignment only on the front wheels. Today, however, most vehicles
on the highway are front-wheel drive (FWD) and on these vehicles, four-wheel
alignment is necessary. On a FWD vehicle the each rear wheel must follow exactly
in the path of the wheel in front of it. If the rear wheels take even a slightly
different path than the front, a condition called rear axle steer results.
This condition makes the vehicle difficult to control, affects vehicle stability
and causes premature tire wear.
How much should an alignment cost? Well, depending upon the vehicle and the
severity of the damage to the front end, you can expect to pay between $75 and
$125 for the average alignment, with exotic vehicles, 4x4s, and other specialty
vehicles costing more.
Peter D. duPre is iCARumba Content Editor.