Know Your Wheels: Tire Types, Replacement and Maintenance

When it comes to maintaining your vehicle, there are a great many systems that can only be evaluated and serviced by a certified mechanic. Monitoring and maintaining the health of your tires is extremely important and is a responsibility that falls to you, the driver. The sophisticated drive features and safety systems in most modern vehicles mean nothing without good traction and a strong connection to the road.

Tires are the rubber, ring-shaped coverings that fit on each of your vehicle’s wheels. Besides protecting the wheel, a tire has two important jobs:

1. Creating the traction which allows you to brake, accelerate and turn.
2. Absorbing impact by bending and flexing to fit the contours of the road.

You may not be the one physically changing the tire yourself but you must still check the tire tread periodically, keep them inflated to the correct pressure and have them replaced, in accordance with the manufacturer’s guidelines.

Tread depth

The pattern of ridges, grooves and markings across the outer surface of the tire is known as tread. This uneven surface creates traction as the tire connects with the road. The grooves in the tread pattern are designed to channel water from the road’s surface away from the raised part of the tread, which meets the road. When the tread wears down, it is unable to channel water properly or provide sufficient traction in wet weather.

As a rule, the grooves in your tire tread should be at least 2/32 inches deep. You can get this depth measured at an auto shop using a tread gauge, or simply keep an eye on the tire wear bars. All modern tires are built with tire wear bars, which appear as thin rubber bars running perpendicularly to the tire’s tread. If these bars are visible at various points around the tire, it is time to get them replaced.

“The penny test” is another great way to check your tire tread. To conduct this test, insert a penny into the tire’s groove with Lincoln’s head facing towards you. Crouch down so that your eyes are level with the tire, to see how much of the penny is exposed. If you can see all of Lincoln’s head, your tire grooves are too shallow.

Different tread types

It can be useful to know about different types of tread when it comes to purchasing new tires for your vehicle. The design and direction of tire tread affects how the surface of the tire interacts with the road, and other materials. Some treads are better suited to certain conditions and purposes than others. The three main types of tire tread are:

1. 1

   Symmetric tread.
   This is the type of tread most frequently found on standard passenger vehicle tires. In these tires, the outer and inner tread patterns are symmetrical (form a mirror image of each other) and the raised portion of the tread forms an unbroken ring around the tire.

2. 2

   Asymmetric tread.
   This type of tread is also used on passenger vehicles, though it is less common. In these tires, the inner and outer portion of the tread pattern follow different designs. The irregularity of this tread pattern makes it good for providing traction in wet, dry or wintery conditions.

3. 3

   Directional tread.
   This type of tread is only found on high-performance tires which are designed to roll in one direction. Directional tread is extremely resistant to hydroplaning and performs well on icy or snowy roads.

Unless you spend a great deal of time driving in extreme climates (either very hot or very cold) or on poorly surfaced roads, standard symmetric tread will probably work for your vehicle just fine.

Tire ratings

Next time you’re shopping for new tires (or even switching a worn tire off your vehicle) check out the numbers and letters printed on the sidewall of the tire. This information tells you how the tire has been rated for wear, traction and heat resistance, in accordance with the Uniform Tire Quality Grading system (UTQG). The UTQG was created by the National Highway Traffic Safety Administration (NHTSA) to ensure all tires meet a minimum safety standard and that consumers can make an informed decision about what they’re buying.

Here’s what those numbers and letters mean:

1. 1

   Treadwear.
   This number tells you how long the tire should last in normal conditions. A rating of 100 is considered standard. Therefore, a tire rated 200 would be twice as hardwearing, a tire rated 500 would be five times as hardwearing – and so on.

2. 2

   Traction.
   This grade tells you how well the tire can maintain traction in wet conditions. Tires are normally rated AA, A, B and C, with AA being the highest level of traction and C being the lowest.

3. 3

   Heat resistance.
   This grade indicates how well the tire can cope with extreme heat. The three levels of heat resistance are A (very resistant to heat), B (moderately resistant) and C (not very resistant). C-rated tires should not be used in very hot conditions.

Always consult your vehicle owner’s manual before purchasing new tires, to find out which grade of tire is best suited to your car and your usual driving environment. Checking out the grading information printed on the tire will help you choose an appropriate set.

Tires for different seasons

Tires generally fall into three categories: all-season, summer or winter. Many motorists opt to keep all-season tires on their vehicle all year round, as these tires are hard wearing and perform well in moderate conditions. Keep in mind that both extreme heat and extreme cold will affect your tire performance. If you live in a state that sees particularly harsh winters or hot summers, you may want to consider switching your standard tires out for seasonal tires during the summer and winter months.

Summer tires

These are often advertised or referred to as performance tires, as they are heat resistant and perform best at temperatures over 45 degrees. Summer tires have wide tread ridges to maximize contact with the road surface. They are typically made with a rubber compound that is softer than that used in all-season tires, which allows them to keep their shape when exposed to extreme heat. Summer tires do not perform well in the cold and become unsafe at temperatures lower than 45 degrees.

Winter tires

Winter tires are built to perform well at temperatures lower than 45 degrees. They typically have deep grooves in their tread pattern to channel water, slush and snow effectively. Across the surface of a winter tire, you will notice thin slits in the tread pattern known as “sipes”; these serve to increase traction in cold, slick and icy conditions. If you decide to switch your tires out for winter tires during the colder weather, make sure all four of your tires are replaced. Having a mix of winter and all-season tires on your vehicle would create uneven traction and may lead to unpredictable handling.

Some winter tires are made with metal studs embedded along the tread. These can dramatically improve traction in extreme, wintery conditions. However, keep in mind that these metal studs can cause damage to the surface of the road. As a result, they are prohibited in many cities and states. Areas that permit drivers to use studded tires generally only do so at certain times of the year. Be sure to check the rules in your city and state.

All-season tires

As the name suggests, all-season tires perform adequately in moderate conditions. They handle hot, cold and wet roadways relatively well and are often longer-lasting than summer or winter tires. If you do not live in a state that experiences extremely hot summers or cold winters and would like to change your tires as infrequently as possible, all-season tires are probably the best choice.

Tire inflation pressure

In addition to monitoring the tread wear on your tires, you will need to check their air pressure every couple of weeks to make sure they are inflated to the correct PSI (pounds per square inch). Your vehicle owner’s manual will tell you the ideal air pressure for your tires, at which traction, impact absorption and fuel economy will be optimized. Over-inflated tires will wear out prematurely, as there is greater pressure forcing the tread against the surface of the road. Under-inflated tires will compress too much as they move over the pavement, causing a build-up of heat that could lead to a blowout.

Always inflate your tires when they are cold. Inflating warm tires will lead to under-inflation, as the air pressure inside them will drop as the tire cools. You can find more information on how regularly you should check tire pressure, in the next article of this module.

Tire rotation

Tire rotation is the practice or periodically switching your front and rear tires. Due to the position of the engine, most vehicles carry more weight on the front axle than they do at the rear, which means tires on the front wheels are prone to wearing faster. Rotating your tires in accordance with the recommended frequency in your vehicle owner’s manual will prolong the life of your tires, so they do not need to be replaced so frequently. How often you should rotate tires differs from vehicle to vehicle, though most manufacturers recommend switching the front and rear tires approximately every 6,000 miles.

Though you may be able to rotate your tires yourself, it is often a good idea to get it done by a professional. That way, the technician can check the alignment of your wheels and adjust them – if necessary – at the same time.

Replacing tires

Rotating your tires will ensure the tread wears evenly, so you should be able to replace them in sets of four. This is better than replacing them in pairs, or individually, as it makes it easier for you to monitor tread wear and keep on top of tire maintenance. Always replace your tires when the tread becomes too shallow, smooth or cracked, as they will no longer be able to provide adequate traction.

Irrespective of visible wear and tear, tires must be replaced at least every six years. The rubber compounds which form the body of the tire are long-lasting but will eventually start to degrade, even if that tire has been sat in a store and never used. Older tires develop poor structural integrity and are more susceptible to tread separation when traveling at high speeds.

Common tire failures

So, what can go wrong if you do not look after your tires? To put it simply: a lot. If you ignore signs that your tires are becoming worn, fail to rotate them or do not keep them properly inflated, they will eventually fail altogether. If this happens while you are driving, it will be extremely difficult to maintain control of the vehicle and avoid a collision.

Here are some of the most common tire problems, and their causes:

Irregular wear

Irregular wear refers to a situation in which the tire’s tread wears down unevenly. This does not always cause serious problems, though it can result in poorer traction and the need for the tires to be replaced prematurely. The three most common types of irregular wear are:

1. 1

   Heel and toe wear.
   Intermittent wear to tread blocks, as a result of normal tire deformation. Moderate heel and toe wear is unavoidable over time, though severe wear could indicate improper inflation.

2. 2

   Center wear.
   The center of the tread pattern appears worn. This occurs more often in vehicles with powerful acceleration where tires are prone to slippage.

3. 3

   One-sided wear.
   This is usually caused by wheel or axle misalignment. If your tire tread is wearing along one side faster than the other, you may need to get your alignment checked out by a technician.

4. 4

   Cupping.
   This appears as shallow patches or “cups” of wear on the surface of the tire. Cupping is the result of uneven contact with the road’s surface, which is caused by wheel bouncing. Cupped tire wear often indicates poorly aligned wheels, low-quality tires or problems with the suspension.

Impact break

An impact break is damage to a cord in the main tire wall and is usually caused by hitting or driving over an obstacle on the roadway. Evidence of the break may appear as a slight bulge in the outer edge of the tire. Impact breaks seriously threaten the integrity of the tire, leaving it more susceptible to tread damage or complete failure. Unfortunately, an impact break means you will need to replace the tire.

Cuts

Noticeable cuts in the surface of your tire are usually the result of coming into contact with sharp objects on the roadway. Cuts do not always render a tire unsafe; it depends on the severity of the damage. Minor cuts should not cause a problem, but larger fissures should be checked out by a tire technician or mechanic. If they believe the tire’s integrity is threatened by the damage, you will need to have it replaced.

Punctures

Like cuts, punctures are the result of encountering sharp objects on the roadway. This may be broken glass, screws, nails or debris from another vehicle. Unlike cuts, punctures are deep enough to penetrate the outer surface of the tire and usually result in a gradual or sudden loss of pressure. If you notice your tire pressure dropping or have discovered an object embedded in your tire’s tread, take the vehicle to be inspected by a professional. In most cases, tire punctures can be repaired without the tire needing to be completely replaced.

Tread separation

Tread separation is a type of irreparable tire failure, whereby the cord beneath the tire’s tread breaks and the tread peels away from the rest of the tire. Tread separation rarely occurs on well-maintained tires that are within their lifespan. When it does, it is usually a result of a manufacturing defect in the tire. Tread separation is a serious risk if you allow your tires to become too worn or too old. This type of failure usually occurs while the vehicle is in motion, often at high speeds, and can result in complete loss of traction and control.

Blowout

A blowout is a sudden and complete loss of air pressure in a tire. Blowouts are often accompanied by an explosive bang, as the body of the tire pops like a balloon. Old or worn-out tires are susceptible to blowouts, though they can also occur in relatively well-maintained tires in extreme heat. In very hot weather, high temperatures and heat build-up between the tire and the road’s surface can weaken the structure of the tire, while causing the air inside it to expand. Tire blowouts often occur with so much force that the driver is powerless to maintain control of the vehicle.

Tire maintenance

Protecting yourself against serious tire failures is not a complicated task. Make sure your tires are correctly inflated and check them regularly for damage, and signs of wear. The information in our next article will help you establish a vehicle servicing routine, to ensure you do not forget to check your tires and perform other essential vehicle maintenance tasks.