Woodstock Auto Repair

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Car Care Tires & Wheels

  1. Checking Tire Tread
  2. Proper Tire Inflation
  3. Tire Rotation
  4. Spare Tire
  5. Tires
  6. Tire Selection
  7. Wheel Alignment
  8. Wheel Balance
  9. Wheel Covers
  10. Wheel Locks
  11. Wheels

Checking Tire Tread

Description: There are several simple ways to check tire tread depth. The first way is to measure tread depth with a tread depth gauge. The second method involves the use of an old penny inserted into the grooves of the tread. Tire wear bars are also used on today's tires as a hands-off visual indication that a tire needs replacement.

Purpose: Regular tread depth checks are important to ensure that your car's tires are safe. Excessive wear can result in a loss of traction, especially on wet and slippery roads. Tires are regular wear items and staying on top of their condition not only ensures your safety, but also gives you the opportunity to plan ahead and budget for inevitable tire replacement.

Maintenance Tips/Suggestions: When using a tread depth gauge, tires need to have at least 1/16-in. of tread or more (this is the minimum amount of tread allowed by law). By using an old penny as a quick reference, insert the penny into the tread groove with the Queen's face showing, but with her head upside-down. If you are able to see all of the Queen's head, the tire needs replacement. (New pennies don't work because of the image of the Queen is too close to the edge). If you see a wear bar across the width of the tread while facing it, it is time to replace the tire.

Generally, it is best to replace tires in sets of four. If your car's tires show signs of abnormal or unequal wear, have this looked into by a professional technician. Excessive wear on both outer edges generally indicates under-inflation. Excessive wear in the centre of the tread generally indicates over-inflation. Cupping or dipping of certain tread sections may indicate worn suspension parts or a wheel balance problem. Saw-toothed or feathered tread edges may indicate wheel misalignment. If your car needs alignment or suspension work, have it done before you drive off with a new set of tires. Taking a "big picture" approach to protecting your tire investment will reap many rewards for miles to come.

Proper Tire Inflation

Description: Proper tire inflation pressure is the specified air pressure given by a carmaker for a certain tire on a specific vehicle. This pressure specification should not be confused with a tire's maximum pressure, which is usually listed on the tire's sidewall. Some vehicles may specify different pressures for the front tires and the rear tires.

Purpose: Correct inflation pressure is critical for good fuel economy, safety, maximum tire life, and proper vehicle handling performance.

Maintenance Tips/Suggestions: For the small amount of time it takes, checking tire inflation at least once a month is one of the best investments you can make to get the maximum life out of your tires. Proper inflation can also improve gas mileage by more than 3%, when maintained regularly. Keep this in mind: Under-inflated tires can lower gas mileage by 0.4 percent for every 1 psi (pounds per square inch) drop in pressure of all four tires. You may want to check your tires more often during the winter months. Tires will lose about 1 psi of pressure for every 10 degrees Fahrenheit of temperature drop.

Keep an accurate tire pressure gauge in your car's glove box (many gauges at "air stations" give false pressure readings) and check the tire pressure when the tires are cold. Never trust the appearance of a tire as a gauge for inflation. A tire could be 10 psi low on pressure and not appear to be low on air. Use the recommended inflation pressure listed in your vehicle's owner's manual or on the inflation sticker found on the driver's door jamb. While you're at it, don't forget to check the spare. There's nothing more annoying than a flat spare when you have a flat tire.

Tire Rotation

Description: Tire rotation refers to the regular practice of switching the position of each tire on the car.
Purpose: Tire rotation helps to equalize tread wear and is critical to gain the maximum life from your tire investment.

Maintenance Tips/Suggestions: Refer to your owner's manual for the recommended rotation interval and pattern; generally a rotation interval of 10,000 kilometres is recommended. The rotation pattern varies with different makes and models, which shows the tire locations during rotation. Some vehicles have different size tires on the front and back or directional tires. This limits the locations that a tire may take on the vehicle. When in doubt, check the owner's manual or consult a professional technician for guidance. Tire rotation time also offers a good opportunity to have the tires and wheels balanced. It is another step you can take to maximize your tire investment.

Spare Tire

Description: Spare tires and wheels may come in full-size versions (the same tire size as is used on the car) or as a "mini-spare", a compact tire and wheel assembly that conserves storage space. Many cars are equipped with temporary spare tires and wheels, which are noticeably different from regular tires and wheels. Some require higher inflation pressure, or the use of a pressurized canister to inflate the tire.

Purpose: The spare tire serves as a back up in case your car has a flat.

Maintenance Tips/Suggestions: Check the air pressure in your spare tire whenever you check tire pressure. There's nothing more annoying than a flat spare when you have a flat tire. It is also a wise idea to become familiar with changing a tire on your car, before you have to.

Acquaint yourself with the location of the jack and its handle, where the jack is supposed to contact the vehicle when raising it, the lug wrench, the location of the key for the wheel locks (if equipped), and how to access the spare tire. Too often, motorists are surprised to find essential tire-changing tools damaged or missing. It is a good idea to make a practice run at changing a tire, so you're on top of things when your car has a real flat. If your car has a temporary spare, drive your car within the limits specified on the tire's sidewall, or until it is convenient to repair the disabled tire or replace it with one of the same size and construction as the other tires on your car.

Always check your car's owner's manual and the tire sidewall for instructions on proper use of a temporary spare.


Description: Tires are simply the wearable and therefore replaceable part of the tire/wheel assembly. Although many different types of tire designs have been used since the dawn of the automobile, the radial tire has virtually replaced all other varieties. Radial tires, by far, deliver better safety and handling, fuel economy, steering, traction and cornering. The typical radial tire consists of a bead, a casing, belts, and tread.

Today, nearly all tires have belts made from steel. Radial tires also last much longer than any previous tire design. Although driving habits and tire care play a key role in tire life, radial tires may last as long as 160,000 kilometres. Virtually all of today's tires used on automobiles, and many used on light trucks, have a tubeless design. This means there is not a separate balloon-like tube inside the tire, as was the case with older tire designs.

Purpose: Tires serve as the wearable part of the overall tire/wheel assembly, but they also play a large role in vehicle safety. Today's tires must provide good traction under a wide range of driving and road conditions while providing long tread wear.

Maintenance Tips/Suggestions: Check tire pressure frequently and also inspect the tires for abnormal tread wear and cuts and bruises along the sidewall. Rotate and balance the tires on a regular basis. If your car has a flat, have the tire professionally repaired. Since most flats are caused by damage to the tire, such as a puncture, anything less than quality repairs can affect the integrity of the tire. The best way to repair a tire is to have it removed from the rim, the inside inspected and corrective measures taken. The quick plug, done from the outside, is no longer recommended by the tire industry. According to experts, the repair could fail, inviting a blowout. When replacing tires, install only tires of the size recommended for your vehicle. Installing the wrong tires can result in contact with body panels or steering and suspension parts. The wrong tires can also affect speedometer readings and engine/transmission control.

Tire Selection

Description: Tires have a coding system all their own that indicates key things like size, application, speed rating, treadwear factors and some others. All of this information is represented through an ordered series of numbers and letters on the sidewalls of tires.

Purpose: Tires are a normal wear item and eventually you'll be faced with replacing them. When you do, making the right choices can make a big difference in your satisfaction once your new tires are installed.

Maintenance Tips/Suggestions: With a P225/75R15 tire as an example, "P" represents passenger car applications (LT=Light Truck), 225 indicates the width of the tread in millimetres, 75 represents the aspect ratio (width of the tread, divided by sidewall height), "R" means radial construction (most tires nowadays) and the 15 means the diameter of the wheel in inches. A tire may also carry a speed rating, which represents the maximum safe driving speed for a given tire. If this is the case, the rating will precede the "R". Speed ratings range from "S" to "Y", which represent 112 and 186 miles per hour respectively. (Speed-rated tires are usually used in high-performance applications.)

In most cases, cars and minivans are originally equipped with passenger car tires, whereas larger vehicles like pickups, SUVs and the like come equipped with light-truck tires. It's important to stick with the size tires and types as recommended by your car's manufacturer or in a tire application guide from a tire maker. Using tires of the wrong size can interfere with steering and suspension parts and it can affect the accuracy of your car's speedometer along with onboard control technology such as the transmission and anti-lock brakes.

There are three other factors that may be helpful in your tire selection process. These three "T" are treadwear, traction and temperature. As with tire sizes, the codes for these are marked on the sidewall of the tire, too. The treadwear number is a relative indicator of just that the higher the number, the better. In theory, a treadwear index of 200 means that the tire will last twice as long as a tire with a 100 index.

Next, comes the traction index, which is expressed as a letter. A tire that performs well during braking on both wet concrete and asphalt gets an "A" index; a tire that performs well on only one of the surfaces gets a "B" index; and a tire that performs poorly on both surfaces gets a "C" index.

The last of the "T" is temperature resistance. An "A" index means the tire has a high resistance to temperature; "B" means a medium temperature-resistance and a "C" index indicates that the tire meets basic safety standards.

There are still other considerations that go into formulating a tire choice that's just right for your car, based on personal preferences. This may include the type of tread for on- or off-road use, the amount of noise the tires produce when driving on paved surfaces and other appearance-related options like raised white letters or black sidewalls.

Wheel Alignment

Description: Wheel alignment consists of a series of interrelated measurements and adjustments that bring a vehicle's steering, suspension and on-road driving characteristics into manufacturers specifications.

Purpose: Proper wheel alignment reduces tire wear, improves fuel economy and handling, while increasing driving enjoyment and safety.

Maintenance Tips/Suggestions: Have your car's alignment checked once a year. Normal wear and road conditions can take their toll on your car's steering and suspension system, possibly throwing the alignment settings out of specifications. For best results, seek a reliable alignment shop and qualified technician who can perform a four-wheel alignment on your car.

Traditionally, alignments have always been associated with only the front wheels, but no longer. Consider this: The rear wheels set the direction of vehicle travel; the front wheels steer the vehicle. Having all four wheels checked ensures directional harmony as your car goes down the road. Some common symptoms of your car needing an alignment include uneven tire tread wear, pulling to one side, wandering, and an off-centre steering wheel. Start an annual routine of alignment checks and you won't have to experience reduced tread wear and a loss of vehicle performance. While having your car's alignment set, it also serves as the perfect opportunity to balance your car's wheels.

Wheel Balance

Description: Wheel balance refers to the proper distribution of weight around a revolving tire and wheel assembly. Poor wheel balance can have a marked impact on both your car and your safety.

Purpose: Proper wheel balance ensures that the wheels, while spinning, do not have a heavy spot that can cause vibration and premature wear of tires, struts, shocks and other steering and suspension components. When combined with proper wheel alignment, balanced wheels ensure smooth and enjoyable driving.

Maintenance Tips/Suggestions: The most common signs of unbalanced tires are vibration and noise problems. When driving with an out-of-balance wheel, the wheel literally bounces down the road rather than spinning smoothly. This can affect the speed, handling and mileage of your car. Many of today's cars have lightweight suspension systems and are therefore, more sensitive to imbalance than older cars. It is a good idea to have your car's wheels balanced when rotating the tires, about every 10,000 kilometres. It is not uncommon for wheels to lose a wheel weight from time to time; so periodic balancing minimizes the impact of unbalanced wheels on your car.

Wheel Covers

Description: Wheel covers, commonly called hubcaps, attach to a steel wheel with a series of retention clips at the outer edge. Steel wheels usually take a full wheel cover or hubcap. Some upscale wheel covers also use a separate anti-theft retaining screw with a separate cap or cover. Aluminum wheels generally use a smaller centre cap that covers the hub and lug nuts and are either a machined finish or painted finish with a hard clear coating.

Purpose: Wheel covers dress up the appearance of cars with standard steel wheels.

Maintenance Tips/Suggestions: Wheel covers should be cleaned periodically when washing your car using a suitable cleaner. When changing a tire, use care when removing the wheel cover to make sure you don't damage or dislodge one of the retention clips. Bent or missing retention clips are the main reason wheel covers fall off. When reinstalling the wheel cover, use extreme care not to break or bend the retention clips. This is especially true on wheel covers with plastic clips. Apply pressure to the wheel cover evenly and gradually; do not force the cover on.

To make sure the cover is fully seated, use a rubber mallet if possible and tap gently and evenly around the cover's edge. When installed properly, the cover should be evenly seated around the edge of the wheel. If you should lose a wheel cover, there's no need to go to your car dealer. There are numerous sources of wheel covers from the automotive aftermarket.

Wheel Locks

Description: Wheel locks function like regular lug nuts, with the exception of requiring a special key tool for removal and installation.

Purpose: Wheel locks help to prevent theft of expensive aluminium and alloy wheels, along with their tires. Wheel locks are also available for spare tires.

Maintenance Tips/Suggestions: Keep the key to your wheel locks in a convenient place (glove box) so it will be available when you need it. If the key is used when your car is in for service, check to make sure that it has been returned to the place where you keep it. Finding out that you don't have the key when it is time to change a flat tire can turn a minor inconvenience into a major aggravation. It is also a good idea to record the code from your wheel locks and order an extra key if possible.


Description: Wheels can be made of steel, aluminum or various alloys. Steel wheels often have a wheel cover affixed to the outer edge for appearance.

Purpose: Wheels support the tire and must be able to withstand loads from acceleration, braking and cornering. Aluminum and alloy wheels also serve an aesthetic purpose and dress up the vehicle's appearance.

Maintenance Tips/Suggestions: Wheels should be cleaned frequently using a suitable wheel cleaner. Use extreme care not to use any abrasive pads or cleaners that may remove the protective coating and scratch the wheels. It is best to clean the wheels while they're cool. Clean one at a time and rinse all cleaner away. Wheel cleaner should not be allowed to sit on wheels for extended periods.