# All parts of a car wheel with pictures, Functions [Explained]

The wheels are one of the most important components of an automobile since, without them, the car cannot accomplish its primary purpose of moving along the road. Thus in this article, we are discussing the parts of a car wheels and their important functions.

Contents:

## Parts of car wheel:

All parts of a car wheel are essential for moving the vehicle along the road, as well as for steering and for stopping it. All of these major components of the car wheel are as follows,

1] Wheel disc
2] Rim
3] Tyre
4] Wheel hub
5] Valve

All of the above components of car wheel are not only part of the wheel structure, but also serve to control the car’s movement. The following figure is the car wheel showing the position of each part in the car wheel assembly.

Let’s discuss all the parts of a car wheel diagram along with its function.

### Tyre:

The tyre is the protective ring mounted around the rim. It is like a cushion provided around the wheel rim.
It is used to absorb road shocks and to provide traction to move the vehicle on road. It is the component of the car that actually deals with the road and supports the weight of the vehicle.

It is inflated with compressed air, which provides shock-absorbing properties to the wheel.

Functions of tyre:

The car tyres perform the following important functions:-

A] Provides the necessary traction to move the car on the road:
The tyre’s contact surface with the road has a higher coefficient of friction. As a result, it aids in the transmission of enough traction to the tyres. So that the car can move onto the road.

B] Provides frictional force necessary to stop the vehicle:-
The braking torque applied to the wheels stops the rotational motion of the wheel. If there is no frictional resistance present between the road and the tyre, then the vehicle will skid on the road due to the inertia force acting on the car.

But because of the presence of a better coefficient of friction between road and tyre, sufficient frictional force is developed by the road that helps to stop the vehicle.

C] Helps to turn the car:
When a vehicle travelling in a straight path suddenly turns, the frictional force acting on the front tyres prevents the vehicle from sliding in a straight line. Thus instead of skidding, the vehicle can change its direction of motion.

The tyre absorbs the shocks from the irregular roads. It acts as a shock absorber for the unsprung masses on the cars.

E] Protects the rim:-
The tyre acts as a cushion for the rims, protecting them from shocks caused by uneven roadways.

### Wheel rim:

Rim is the outer part of the wheel on which the tyre is mounted. The bead of the tyres fit into the edges of the rim to ensure strong contact between them.

The rims are made up of the same material as the wheel disc. In the case of spoke wheels, the rims have holes for fitting the spoke with nipple.

In tubeless tyres, the rims have a smooth surface to make an airtight contact with the bead of the tyre.

Functions of wheel rim:-

Following are the different important functions of the wheel rim:-

A] Holds the tyre:-
The profile of the rim is designed in such a way that it properly holds the bead of the tyre. The rim makes firm contact with the tyre, thus it can transmit the traction and braking force to the tyres.

B] Sealing in the tubeless tyre:-
The rim of the wheel creates a properly sealed contact with the bead of a tubeless tyre. Generally, the rims of cast alloy wheels are suitable for using tubeless tyres.

While the rims of the spoke wheels have holes for the fitting of the spoke nipples, thus these are not suitable for the tubeless types.

C] Resist lateral forces:-
The rim also bears the lateral load coming onto the wheel while taking a turn.

### Wheel disc:

The wheel disc is the central metal or the cast-alloy component of the wheel other than the rim. It helps to transfer the driving and braking torque from the wheel hub to the rim and tyre.

The wheel disc has holes for mounting it on the wheel hub and also has holes for the cooling of brake components mounted on the wheel.

Functions of wheel disc:-

The functions of the wheel disc are as follows:-

A] Transmit torque to the rim:-
The disc transmits the driving torque and braking torque from the wheel hub to the rim of the wheel.

The disc of the wheel absorbs some amount of shocks coming from the road irregularities.

C] Supports weight of the vehicle:-
The disc of the wheels supports the load of the vehicle.

D] Helps to cool the brake:-
The disc has holes on its surface, that increase the flow of air over the brakes. Hence it helps to dissipate more heat from the brakes and cools them faster.

E] Holds the rim:-
It is the primary function of the disc to hold the rim and wheel hub together.

### Wheel hub:

The wheel hub is the central part that joins the drive axle to the wheel disc. The wheel disc is mounted onto the wheel hub with the help of studs, thus it transfers torque from the driving shaft to the wheels.

It also holds the rotor of the disc brake, thus it helps to stop the wheels during the application of the brake.

Functions of wheel hub:-

Following are the important functions of the wheel hub:-

A] Holds the wheel disc:
The wheel hub holds the wheel disc by means of the studs or bolts. While the other end of the wheel hub is connected with a spline drive shaft. Thus the wheel hub transmits the power from the drive axle to the wheel.

B] Housing for bearing:-
The bearing is mounted on the wheel hub therefore it also works as bearing housing.

C] Holds the rotor of the disc brake:-
The rotor of the disc brake is held between the wheel hub and the wheel disc, thus the wheel helps to transmit the braking torque from the disc brake rotor to the wheel.

D] Helps to steer the car:-
In the case of steered wheels, the wheel hub is mounted on a steering knuckle, thus it helps to steer the wheels while taking a turn.

E] Housing for ABS sensor:-
The ABS sensor for monitoring the wheel velocity is mounted onto the wheel hub.

### Valve:

The valve stem for the tubless tyre is mounted onto the rim of the wheel.

As tubeless tyres never use tubes, thus in this case the valve stem is mounted into the hole provided on the rim for inflation of the tyre and to hold the air pressure.

## FAQs:

1. What is the part of the car that goes over the wheel?

The tyre is mounted over the wheels.

2. What is the middle part of a car wheel called?

The middle part of the car wheel is known as the wheel hub.

3. What connects the tire to the car

The metal or alloy wheel connects the tire to the car.

The car wheel is made up of the above 5 essential parts, and without anyone of them, the wheel assembly remains incomplete, limiting the car’s functionality. Therefore in this article of ‘Parts of a car wheel’, we have discussed the five different parts of a car wheel assembly with their names and functions.

I hope you find this information interesting. If you get stuck at any part in this post, leave a comment below, I’ll respond to you soon, as well as don’t forget to share what you’ve learned with your friends.

Pratik is a Graduated Mechanical engineer. He enjoys sharing the engineering knowledge learned by him with people.