Your car drifts slightly to the right on a straight road. The steering wheel sits off-center when you drive straight. The inside edge of your front tires is wearing faster than the rest. These are classic signs of an alignment problem.
Wheel alignment adjusts the angles of the wheels relative to each other and to the vehicle. Even small errors can increase tire wear and affect handling.
Key Takeaways
- Toe is the inward or outward angle of the wheels viewed from above; incorrect toe is a common cause of rapid tire wear.
- Camber is the inward or outward tilt of the wheel viewed from the front; excessive camber wears one edge of the tire.
- Caster is the forward or backward tilt of the steering axis; it affects steering stability and return-to-center.
- Get an alignment after hitting a large pothole or curb, replacing suspension or steering parts, or when you notice pulling or uneven wear.
Toe
Toe describes whether the fronts of the wheels point slightly toward each other (toe-in) or away from each other (toe-out), viewed from above.
Incorrect toe causes the tires to scrub sideways as they roll, producing a feathered wear pattern across the tread. Toe is the most common alignment adjustment and has a large effect on tire life.
Symptoms: rapid tire wear, feathered tread, steering wheel off-center.
Camber
Camber is the inward or outward tilt of the wheel, viewed from the front.
- Negative camber: top of the wheel tilts inward.
- Positive camber: top of the wheel tilts outward.
A small amount of negative camber can improve cornering grip. Excessive camber concentrates wear on one edge of the tire.
Symptoms: wear on the inside or outside shoulder of the tire, pulling toward the side with more positive camber.
Camber is not adjustable on all vehicles without additional parts. Out-of-spec camber may indicate bent or worn components.
Caster
Caster is the forward or backward tilt of the steering axis, viewed from the side. Positive caster helps the steering return to center and improves straight-line stability, similar to how the front wheel of a shopping cart trails behind its pivot.
Uneven caster from side to side can cause pulling. Caster has relatively little direct effect on tire wear.
Thrust angle
Thrust angle describes the direction the rear wheels are pointing relative to the vehicle’s centerline. If the rear wheels are misaligned, the vehicle can “crab” slightly, and the steering wheel may be off-center. A four-wheel alignment considers thrust angle.
Reading tire wear patterns
- Feathered edges across the tread: often toe
- Inner or outer shoulder wear: camber, or toe in some cases
- Center wear: over-inflation
- Both shoulders worn: under-inflation
- Cupping (scalloped dips): worn shocks or struts, balance problems or other suspension issues
Wear patterns can have more than one cause, so a technician should inspect suspension and tire pressures as well as alignment.
When to get an alignment
- After hitting a large pothole or curb
- After replacing steering or suspension components such as tie rods, control arms, struts or ball joints
- When installing new tires, to protect your investment
- If the vehicle pulls, the steering wheel is off-center, or tires wear unevenly
- As part of periodic maintenance; some manufacturers suggest checking alignment regularly
Reading an alignment report
Many shops provide a printout showing:
- Before and after readings for toe, camber and caster
- Specification ranges, often shown with green (in spec) and red (out of spec)
- Front and rear values, and sometimes thrust angle
Ask for the report. If values are out of spec but were not adjusted, ask why; some angles require parts to adjust.
Alignment vs balancing
Alignment and balancing are different:
- Alignment adjusts wheel angles.
- Balancing corrects uneven weight distribution in the wheel and tire, which causes vibration at speed.
A vibration that increases with speed often points to balancing rather than alignment.
Frequently Asked Questions
How long does an alignment take? Often about an hour, longer if parts are seized or need replacement.
Can bad alignment affect fuel economy? Severely misaligned wheels can increase rolling resistance.
Why does my car still pull after an alignment? Tire conical forces, uneven tire wear, brake drag or road crown can cause pulling.
Should I get a two-wheel or four-wheel alignment? Most modern vehicles benefit from a four-wheel alignment check.
The bottom line
Toe, camber and caster determine how your tires meet the road. Watch for pulling, an off-center wheel and uneven wear, and get an alignment after impacts or suspension work.