Wheels and tires are often mistakable used interchangeably. Tires are the rubber that’s wrapped around each wheel. Wheels are made of metal and connect the tire to the rest of the vehicle.
Brakes are responsible for stopping the entire vehicle, but they are often overlooked as a vital part of the car or truck. The whole wheel, tire, and brake assembly may be the most misunderstood part of a vehicle, at least to the average consumer.
So why are they all so important? We’re going to look at that today and hopefully give you a better understanding of the parts that make your car stop and go.
Wheels:
Wheels come in all kinds of different materials, sizes, and styles. Wheels come in different weights as well. The type of vehicle you buy will often dictate which wheel size, type, and material will be used.
Steel:
Steel wheels are often used on base model cars because they are less expensive, less durable, and less attractive than other types of wheels. They are recognizable by the plastic wheel covers, or lack thereof, that mask them. Most steel wheels are black in color and will rust over time.
Alloy:
Alloy wheels are made from any number of different metals, including aluminum, carbon, and magnesium. They are usually available on mid to high trim levels on most vehicles, and they can be lighter than steel wheels. Though they won’t rust, brake dust can build up causing long-term damage to their appearance.
Most normal vehicles that don’t have steel wheels have some type of alloy wheels. They can come in a variety of colors ranging from grey to black and even more colors if they’re painted. They also provide greater strength and durability than steel wheels.
Alloy wheels are preferred in performance cars because of their durability, strength, and lack of weight.
Weight:
Weight is the enemy of many things, especially performance. Most of us won’t notice any kind of difference in the weight of whatever kind of wheel is on our vehicle, but in motorsport, it matters quite a bit.
Even for those who occasionally participate in autocross events or have a high-performance vehicle will probably put aftermarket wheels on their vehicle. In racing, every little ounce counts. The right wheels can make a huge difference.
Size:
Weight and material aren’t the only things that matter when it comes to wheels. The size of the wheel is most likely going to impact the ride quality of your vehicle. Your vehicle has wheel wells specifically designed for your vehicles stock wheel size. Any size different than your manufacturer suggests will probably require some time of adjustment to some aspect of your chosen wheel setup.
The size of your wheel is going to dictate the size of the tire you can equip to your vehicle. Every car is designed with a specifically-sized wheel in mind. If you like the sporty look of a larger wheel, you will have to get a skinnier tire so it can fit inside the wheel well.
The size of the wheel also has an effect on the overall appearance of a vehicle. Generally speaking, a larger wheel will make a vehicle look sportier. This isn’t always the case, but it is almost always the case that a sports car will have larger wheels than a family sedan or even a truck or SUV.
Offset:
Chances are that most people aren’t going to care much about offset. If you are looking for wheel upgrade, it may be a factor in the wheels you choose. Offset is the distance, in millimeters, between the mounting hubs in the center of the wheel to the actual center-line of the wheel.
This is important for clearance issues for both the brakes and the space available in your vehicles wheel wells. If you replace your wheels, getting ones with an incorrect offset could cause tire rubbing or may not fit over the brakes.
Tires:
Much can be said of tires. They are the only part of the entire vehicle that is in contact with the surface of the road. Their quality, durability, and function is vital to a vehicle’s performance. In the case of tires, even the average person can tell if the tires they have are good or bad.
Like many other products, people don’t understand that millions of dollars are spent developing everything about what a tire is and does. This is why they can be so expensive. Despite this, they are all designed specifically to keep your vehicle and all its occupants safe in any condition.
Tread Pattern:
The first thing most people notice about a tire is its tread pattern. Tread pattern is the grooves, indentations, and channels on the surface of the tire. They can be made to grip wet, snowy, or muddy surfaces depending on the type of tire.
Most stock vehicles are going to have a basic road tire. Their tires’ tread pattern is about what you’d expect in a normal vehicle. More aggressive tread patterns with deeper grooves are built for off-road vehicles like Jeeps and other trucks. Performance tires usually have fewer grooves to increase surface area and improve grip.
Compound:
Tire compound is the general makeup of a tire. Depending on the quality and purpose of each tire, a harder or softer rubber will be used.
Tires built with harder tire compounds are usually less expensive and are more often found in everyday vehicles. They don’t wear as quickly, but they also aren’t built for performance.
Softer tire compounds are used more for performance. They have better traction, because they can conform to road surfaces. They also heat up more quickly which can improve traction. Of course, softer tire compounds are not usually as durable as tires with harder compounds.
Types:
There are five basic types of tires. All have their own sub-types, but all are designed for a specific purpose.
All-Season:
All-season tires are fitted to most average vehicles from the factory. They are an all-around tire that offer the best all-around performance for what most people need. Most good all-season tires will last from anywhere between 40,000 and 70,000 miles.
Off-Road:
Photo: Courtesy of OffRoad.com
Off-Road tires can include mud or dirt tires. You can see these on trucks and SUVs such as Jeeps. They are usually big, bulky, and have aggressive tread. Sometimes, their tread is so aggressive, you can hear them “hum” as a vehicle equipped with them drives by.
Snow:
Snow tires are built specifically for the snow. They don’t have tread as aggressive as some dirt tires, but their tread is more aggressive than all-season tires, much like you’d expect. They have many smaller and narrower channels throughout the tread to provide the best possible traction in slippery conditions.
Snow tires aren’t ideal for normal, warm weather driving as their traction is actually reduced under normal weather conditions. People who have snow tires often have a second set of all-season tires because of this.
Sport:
Sport tires are made of a softer compound than all-season tires and generally have fewer channels and grooves. More tire surface and a softer tire compound provide better grip for more performance-oriented vehicles. These are sometimes referred to as “summer tires.” A good set of sport tires will last from anywhere between 20,000 and 40,000 miles.
Performance:
Tires with the softest compound and usually the least amount of tread are performance tires. Drag slicks, racing tires, and performance road tires all fit in this category.
Some performance tires like those used in NASCAR don’t have any tread so that the most amount of tire surface is in contact with the pavement. This improves grip to a greater extent than the use of a soft tire compound alone.
Most racing and drag tires aren’t street legal, and those performance tires that are legal rarely last more than 15,000 to 20,000 miles.
Size:
Photo: Courtesy of Tire and Wheel Xperts
Size is a big factor in how much the tires are able to grip the road and how comfortable a vehicle’s ride is. Tire size is measured by three main designations: Width, aspect ratio, and wheel size.
You may have been shopping for new tires at some point and simply put your vehicle’s make and model in the computer to see a full selection of available tires. You should have also seen a series of numbers and letters beside each tire. Each of those stands for some aspect of tire size.
We will use a base model 2018 Toyota Camry and a 2018 Dodge Challenger R/T as examples. The Camry has a stock tire size of 205/65 16. The Dodge Challenger R/T, which is equipped with a V8 engine, has a tire size of 245/45 20.
The first number is the width of the wheel, the second number following the backslash is the measurement of the aspect ratio, and the last number is the size of the wheel on which the tire fits.
Some performance vehicles have a staggered tire setup. This means that the front and rear tires are sized differently. Vehicles with a staggered tire setup are usually rear-wheel drive performance vehicles and supercars. Drag cars are also set up this way to improve off-the-line acceleration. Cars you can buy with a staggered tire setup include the Ford Mustang, Chevrolet Camaro, and Chevrolet Corvette.
Width:
Simply put, a wider tire will generally provide better grip. A wider swath of rubber contacting the road means that there is more material that can grab the road surface. The first number in the tire size designation is measured in millimeters. The larger the first number, the wider the tire will be.
The Challenger, mentioned above, has a tire width of 245 millimeters as opposed to the Camry, which has a width of 205 millimeters. This is understandable seeing as how the Challenger has much more horsepower, thus requiring a larger amount of traction to put its power to the pavement.
Aspect Ratio:
The second number in the tire size designation is aspect ratio. Another word for aspect ratio is profile or sidewall, which is just another way of saying that it’s the visible part of the tire that doesn’t contact the pavement.
This is measured by using a percentage of tire width. In other words, the Camry’s tire aspect ratio is 65, which means that the side of the tire is 65% of the width of the tire. The Challenger’s tire aspect ratio is 45, making it’s sidewall 45% of the tire’s width.
The size of the aspect ratio effects the ride of a vehicle. Along with the suspension and type of vehicle, a car with an aspect ratio of 65 as opposed to 35 will most likely provide a more comfortable riding experience. Less rubber means less cushioning and road imperfection absorption.
Diameter:
Wheels come in all different sizes. The last number in the tire size designation is simply how large of a wheel the tire can accommodate. The Camry’s tire fits a 16 inch wheel, while the Challenger’s tire fits a 20 inch wheel.
Other Tire designations:
The number designations on a tire are there for size, but there is more information on a tire than just size. Along with the numbers we’ve already mentioned, there are a few letters that get added to complete the tire setup. The full tire designation for the Camry is actually P205/65R 16, and the Challenger is P245/45R 20.
The first letter designates the type of the tire, and the second letter designates its construction. Furthermore, some tires have additional info on the side to show its load capacity and speed rating.
Metric:
The “P” at the beginning of the sequence stands for “passenger metric.” It’s the most commonly seen type of tire. Other variations of this include the euro-metric, which usually isn’t designated with any letter, and “LT” which stands for “light truck.” “LT” metric tires are used in vehicles which carry trailers and large loads.
Construction:
The “R” stands for “radial.” This simply means that the tires are made in a way such that the layers of the tire are essentially wrapped around in circular motion to create the tire.
Load Capacity:
Load capacity is the amount of weight a tire can bear when filled appropriately.
Speed Rating:
Speed rating is the maximum speed at which the tire is able to function safely. Each speed range has a letter designation showing its maximum speed capacity.
Brakes:
Brakes do a lot more than we give them credit for. Just think about it. Brakes have the capability to stop a fully loaded vehicle going 70 miles per hour or more! That is not an easy task! Of course, how well the brakes do that is dependent on brake quality, size, and the actual weight of your vehicle.
Brake Types:
Photo: Courtesy of Mechanicalbooster
There are several different types of brakes commonly found in cars and trucks. Air brakes and “jake” brakes found in trucks are a different matter for a different day.
Disc Brake:
Disc brakes have become the most popular kind of brake used in vehicles today. It gets its name from the shape of the rotor. A disc brake looks like a flat, round plate.
Drum Brake:
Drum brakes were the brakes of the past. You can still see them in some very inexpensive vehicles today in order to keep costs lower, but even then, just about every vehicle with drum brakes only uses them on the rear wheels.
Rather than using a caliper to squeeze and stop a disc brake, a drum brake is encased in a housing and pushes on a rotating drum. These are generally not as effective as disc brakes.
Emergency/Parking Brake:
In most cases, the emergency or parking brake uses a set of cables to mechanically apply pressure to the wheels of a vehicle as an added safety measure or in case of an emergency stop. Even electric parking brakes still use cables even though they are electronically controlled rather than manually controlled by controlling a lever or pedal.
Most parking brakes are engaged by pulling a lever or pushing a floor pedal. Today, those levers and pedals are being replaced by switches and toggles.
Now onto the brake assembly itself… There are a few main components that make up each brake assembly.
Rotor:
The brake rotor is the round metal part of the brake you can see through the wheel of your car. It spins with the wheel and can be made of several different materials including cast iron, steel, and carbon ceramic.
There are also several different types of brake rotors that all have different benefits. Types of rotors include blank, vented, and slotted or drilled. Blank brake rotors are found on most vehicles and have a flat surface. Vented rotors have channels that aid in cooling, and slotted or drilled rotors have holes throughout the rotor.
Photo: Courtesy of R1 Concepts
Vented and slotted rotors are often used in performance vehicles due to their heat dissipating ability and their potential weight savings. Some brakes are even designed with both vents and slots to provide the best of both setups.
Caliper:
Photo: Courtesy of Z1 Motorsports
The caliper is the stationary clamp that bites down on the rotor and stops the vehicle when you press the brakes. Calipers themselves house the brake pads which actually contact the rotor, but calipers contain the pistons that allow the brakes to grab.
Brake Pad:
Brake pads are what come into contact with the brake rotor when the brakes are applied. They fit inside the caliper and come in several different types including metallic, non-metallic, and ceramic.
Other Wheel, Tire, and Brake assembly terms:
Though we’ve looked at the basic components of the wheels, tires, and brakes, there are a few more things that pertain to these systems that we have to cover. Here are a few:
ABS:
ABS stands for “Anti-lock Braking System.” It is standard on every car sold in the U.S. today. ABS can be felt and heard during hard braking or during braking on a slippery surface. It electronically grabs and releases the brakes automatically several times a second to add braking control in emergency situations.
Contrary to popular belief, ABS does not necessarily decrease breaking distances. Rather, it helps control a vehicle in hard braking situations. Locking the brakes of a car can cause a vehicle to spin and drift. ABS prevents locking and therefore the driver can control the direction of travel of the vehicle.
Camber, Caster, and Toe:
Camber, Caster, and Toe all play an important part in the alignment of tires and wheels. Excluding caster, camber and toe can be easy to see upon close inspection if both are severe enough. All have a profound effect on both normal driving and motorsport.
Camber:
Photo: Courtesy of Pro Car Mechanics
Camber is the vertical alignment of each wheel and tire. Normally, a wheel and tire should form a 90 degree angle with the road surface.
Positive camber occurs when the top of the wheel and tire lean farther outward than the bottom. Negative camber occurs when the top of the wheel and tire lean toward the vehicle. Negative camber is much more common and can be seen when a car is loaded down or in lowered cars so the wheels can fit inside the vehicles wheel wells.
Both negative and positive camber have a tremendous impact on tire wear. Both can result in uneven wear and potential blowouts while driving.
Caster:
Caster is the angle at which the steering pivot of a car meets its vertical axle. A good example to see what caster looks like is a bicycle or motorcycle. In a bike or motorcycle the prongs that attach the front wheel to the handlebars represent caster.
Most bikes and motorcycles have a positive caster angle, pushing the wheels farther forward than the front handlebars. Caster can change the handling characteristics of a car.
Toe:
Photo: Courtesy of Come and Drive It
Toe angle is the angle at which the wheels of a vehicle face forward and backward. Ideally, the wheels of a car would be completely parallel with each other. A negative toe angle occurs when the wheels point away from the inside of the vehicle. Positive toe occurs when the wheels are pointing toward the inside of the vehicle.
Like camber, negative and positive toe angles can prematurely wear down tire tread. Getting an alignment on your car can fix toe and prevent tire damage, premature wear, and a potential blowout.
Unlike many of the engine or drivetrain components we’ve talked about over the past couple weeks, you will probably have to replace tires and brakes several times during your vehicle’s lifespan. Both tires and brakes wear out. It will be easier for you to make an informed purchase with a basic understanding of everything we’ve just covered.
Just remember never to overlook your wheels, tires, and brakes. They are quite possibly the most important pieces of equipment on your car, and they are some of the only things standing between you and coming to a full and safe stop behind the car in front of you.
