• Tires
  • Brakes
  • Suspension
  • Alignment

Tire wear can be a warning sign of other vehicle problems. Don’t assume worn tread means your tires are getting old – your safety depends on it.

arrowdown Wear Patterns

Excessive wear on either edge
Tire will look almost bald on the inner or outer edge, while the rest of the tread looks intact.

The most common reason for this type of wear is that the tire is leaning too much to the inside edge (negative camber) or too much to the outside edge (positive camber). This places all the work on one side of the tire causing excessive wear.

See more on Camber under Alignment.

Excessive wear on both outer edges
Under-inflated tires typically cause this type of wear. When your tires are under-inflated the tire sags and the outer edges come into greater contact with the road. The spreading of the tire creates excessive wear patterns on the outer edges, while the middle looks intact.

The exact opposite wear pattern is true for over-inflated tires. Tires appear worn in the middle, while tread on the outer edges remain intact.

Cupped edges
Tire will have cup-like indented patterns along the inner or outer edge.

This is typically caused by a combination of improper toe along with worn shock absorbers and/or improper balance. See more on toe and shock absorbers under Alignment and Suspension Systems.

Cupping
Tire will have deepened (concave) areas of wear across the surface.

This usually occurs when the same spot(s) on the tire are repeatedly exposed to more pressure than other areas, typically due to improper balance or worn shock absorbers.

See more on shocks under Suspension Systems.

Feathered edges
Tire will have worn edges with feather-like patterns.

Typically feather-edge wear is caused by alignment issues such as improper toe. Excessive toe literally drags the tire sideways. Sideways drag combined with tire rotation creates the feathered edge. This can happen when the front axle toe is incorrect. Excessive toe-in scrubs the tires so that the high end of each feather points toward the center of the vehicle. Excessive toe-out creates a feather pattern pointing outward.

arrowarrowdown Tire Rotation

Rotating your tires involves changing their position from one tire location to another. Different tire locations cause different wear patterns. Tire rotation spreads this wear out, and more or less wears the tires evenly, so they last longer.

Tire rotation is recommended by all tire manufactures, and in some cases, every 8,000 to 15,000 miles.

Front wheel drive
The front tires tend to wear at a much faster rate than those in the rear. The front tires may be almost bald, while the back ones have more than half of their tread life remaining.

Recommended tire rotation: Move the rear tires to the front, each to the opposite side, and move the front tires to the rear, each on the same side.

Rear wheel drive
Recommended tire rotation: Move the front tires to the rear, each to the opposite side, and move the rear tires to the front, each on the same side.

Directional tires – same size
Recommended tire rotation: Swap the front and rear tires on the same side.

Directional tires – different size
Recommended tire rotation: Swap the front tires with each other and the back tires with each other.

arrowdown Tire Performance Rating

It is a common misconception that a tire rating designates how fast you can drive on a specific tire for a period of 2 hours before it comes apart.  And that this rating represents a tire’s endurance or the ability to hold itself together.
 
In actuality, a Tire Performance Rating indicates a certain amount of grip on that specific tire. The higher the rating, the stickier the compound or grab on the road. A high Tire Performance Rating decreases the distance needed to stop your vehicle at 50 mph. The stopping distance increases, the lower the Performance Rating.

A tire’s Performance Rating effects the way your vehicle rides and handles on the road. You may need a tire built for comfort or performance, one that grabs the road softer or harder.  We can help you choose the right tire for your passenger car, SUV, truck, performance or touring vehicle. And we recommend the same or higher Tire Performance Rating as required by your vehicle manufacturer.

See our Performance Rating Chart for more information.

arrowarrowdown Tire Tips

Air pressure
Check your air pressure regularly. And don’t forget your spare.

Under-inflated tires increase their wear, and in rain you could lose traction on the road. (In cold weather, your tire can lose a pound or more of pressure for each drop of 10º F.)

Jack-rabbit starts. Screeching stops and turns. Scuffing curbs. All of these driving habits undermine a tire’s lifespan, as well.

Tread
Check your tire tread regularly. The wear should be uniform around the entire tire.

The tread grooves must be at least 1/16 inch deep for the tire to be driven on. See tire wear patterns to learn if your tires are wearing properly.



Wheels should be pulled and brakes checked once a year by an ASE-certified technician. Typically, an inspection includes the rotors, calipers, drums, pads, pistons and brake lines.

arrowdown Disc Brake System

Disc brakes are found on the front of all modern vehicles.

The Main Components

1. Vacuum Booster

2. Caliper Housing

3. Brake Pads

4. Rotor

Pressure from your brake pedal is amplified in the vacuum booster using energy from your engine. This is a crucial part of your braking system as a lack of hydraulic pressure can translate into insufficient pressure between your brake pads and your rotor, which could be dangerous.

The pressurized hydraulic brake fluid is then passed through a complex network of tubes and hoses, along to the pistons inside the housing caliper. This pressure causes the pistons in the interior of the housing caliper to expand and press against the brake pads. The brake pads press against the smooth surfaces of the disc-shaped rotors and the friction stops the wheels from spinning.

arrowdown Drum Brake System

Drum brakes are found on the rear of many vehicles.

The Main Components

1. Vacuum Booster

2. Cylinder Piston

3. Brake Shoes

4. Brake Drum

5. Return Spring

 

Pressure from your brake pedal is amplified in the vacuum booster using energy from your engine.

The pressurized hydraulic brake fluid is then transferred to the cylinder piston. The pressure causes the cylinder piston to expand and press against the brake shoes. The brake shoes, like brake pads, press against the smooth inner surface of the spinning brake drum. The friction forces the brake drum, and the wheel, to stop.

When you release the brake pedal, the return spring pulls the brake shoes away from the brake drum and all components go back to their original position.

arrowdown Brake Tips

Brake check
Wheels should be pulled and brakes checked once a year by an ASE-certified technician. Typically, an inspection includes the rotors, calipers, drums, pads, pistons, and brake lines.

Brake fluid
Brake systems should be flushed and brake fluid replaced every two years. Brake fluid absorbs moisture in the system and becomes acidic after two years or 30,000 miles.

Brake adjustments
Check your owner’s manual or ask your ASE-certified technician about adjusting your brakes. For example, most drum brakes are self-adjusting by backing up or engaging the emergency brake.





Your suspension system is critical in ensuring maximum contact between your tires and the road, absorbing shock forces, and ultimately defining handling performance.

arrowdown Function

The Main Components

1. Springs

2. Shock Absorbers

3. Tires

What does your suspension system do?
Your suspension system performs 4 critical functions.

  • Ensures maximum and continuous contact between your tires and the road.
  • Reduces the effect of shock forces.
  • Supports vehicle weight and maintains correct vehicle height.
  • Maintains correct wheel alignment. See Alignment.
arrowdown Springs

What are your springs?
Springs act as a buffer between your wheels and the rest of your vehicle, absorbing shock from the road by compressing vertically.

What do your springs do?
1. Your springs compress and store the kinetic energy of the shock as potential energy. The energy is repeatedly transferred back and forth until all of it is dissipated. This oscillation between kinetic and potential energy is what causes the bouncing effect of springs.

2. Your springs support the weight of your vehicle, and the weight must be distributed properly among all four springs.  If your vehicle weighs 2000 lbs, the four springs must provide the exact amount of force in the exact opposite direction as gravity (-2000 lbs).

3. Your springs maintain your vehicle ride height defined by design specifications. Worn out springs can’t support your vehicle weight and cause ‘sagging’ which alters the alignment geometry of the wheels and can lead to 1) handling problems, 2) wear on other suspension components, and 3) excessive wear on your tires.

arrowdown Shock Absorbers

What are your shocks?
Shock absorbers keep your springs in line. As your springs compress and expand every time you hit a bump, your shocks keep them from bouncing and bouncing and … Your shocks protect you from getting seasick. They control spring and suspension movement by providing resistance to upward and downward motion of spring and suspension components.

How do your shocks work?
1. Your shock absorbers have a piston and a piston rod inside their main cylinder. The piston and rod serve as a ‘parachute,’ slowing down the flow of hydraulic fluid running thru the main cylinder.

2. When pressure from the road causes the spring to compress, hydraulic fluid is forced out of the chamber with higher pressure into the chamber with lower pressure.

3. As this happens fluid is forced through openings in the piston at a limited pace, restricting the flow. This creates a backward pressure that restricts the up and down motion caused by the bump in the road.


arrowdown Safety Tips

As a critical part of your suspension system, shock absorbers affect the handling performance of your vehicle. Worn and/or old shocks cause your tires to continually bounce. Constant bouncing keeps your tires off the road and tires that don’t grip the road are useless. Good and/or new shock absorbers play a central role in your safety.





Proper alignment plays a central role in your safety. Be aware of signs of improper alignment, including unusual tire wear, unusual steering feel or vibrations.

arrowdown Camber

Camber, measured in degrees, refers to the inward and outward tilt of the top of your wheel. Positive camber for an outward tilt and negative, if the top of the wheel tilts inward.

It is crucial the camber of your wheels remain within the narrow range specified by your vehicle’s manufacturer.

Consequences of positive camber are:

  1. Vehicle will pull to the side with the positive camber
  2. Disproportionate pressure and wear on the outer portion of tire
  3. Extra wear on the suspension

Consequences of negative camber are:

  1. Vehicle will pull to the side with the negative camber
  2. Disproportionate pressure and wear on the inner portion of tire
  3. Extra wear on the suspension
arrowdown Caster

Caster refers to the backward tilt and forward tilt of your wheel, and like camber, is measured in degrees. A backward tilt is positive and a forward tilt is negative.

It is crucial the caster of your wheels remain within the narrow range specified by your vehicle’s manufacturer.

Consequences of improper caster are:

  1. Steering wheels show lack of “returnability” after a turn
  2. Vehicle pulls toward the side with the lowest caster
  3. Steering is touchy and less stable at high speeds
arrowdown Toe

Your two front tires should be parallel to each other, as should your two rear tires. If either or both of your tires are not perfectly parallel you have toe issues, and like camber and caster, toe is measured in degrees. Tires pointing toward the center or your vehicle are positive toe; tires pointing away from the inner axis of your vehicle are negative toe.

Consequences of positive toe are:

  1. Disproportionate pressure and wear on the outer portion of tire. Wear patterns are saw-toothed and scuffed.

Consequences of negative toe are:

  1. Disproportionate pressure and wear on the inner portion of tire. Wear patterns are saw-toothed and scuffed.


arrowdown Alignment Tips

Signs of Bad Alignment

Unusual tire wear
One or more tires will show excessive wear on one side, such as cupped, scalloped, or diagonal striped patterns at edges or across the tread, or show uneven wear, such as featured edges on the tread.

Tires may also be wearing unevenly if they squeal while you are making a turn.

Unusual steering feel
Steering will feel stiffer than normal or the steering wheel will not return to the center position when released.

The steering wheel will drift either right or left on its own while the vehicle is in motion on a level road.

The vehicle will feel skittish and riding on “tip-toes.”

Vibrations
Strong vibrations felt through the vehicle or steering wheel indicate the suspension, or wheels and tires, have mechanical or balancing problems – all which affect alignment.