How Car Wheels Work and Why They Matter

Date Posted: June 20, 2020

sports car wheel

Most people on Earth would agree: wheels are pretty crucial to cars. But why? Other than being responsible for actually moving along the road, what other roles do car wheels play? 

In this article, we take a look at how car wheels work and why they make such a huge impact on comfort, safety, handling and performance.

Firstly, what are the main parts of car wheels?

car wheel without tyre

  • Wheel (rim): If you remove a tyre from a wheel, you have a wheel disc in the center with a rim around it. The rim is the cylindrical part around the edge of the central wheel disc. It’s the rim’s job to hold the tyre on and retain air pressure. Most people refer to a wheel without a tyre as a ‘rim’. In the picture above, the wheel is silver and the rim is black.

 

  • Tyre: Firstly, tyre is British and tire is American. We’re in Australia so we’ll use tyre. Tyres play a huge part in safety, comfort, fuel consumption and handling. So why are tyres filled with air and not just solid rubber? Air cushions road vibrations, acting as a shock absorber. Furthermore, solid rubber tyres are extremely heavy and much more expensive to produce. You need soft, flexible air to help grip the road too.

How Car Wheels Work

luxury car wheels

Car wheels work by softening the bumps and vibrations in road surfaces while providing maximum traction for minimum fuel cost. At least they try to. The quality and condition of the tyres play a huge role in this. The wheel attaches to a hub. Hubs are the part of a car visible if you remove a wheel. They have a circular pattern of bolts (studs) that the wheel attaches to.

Tyre Choice

new tyres

Correct tyres play a large part in car wheels. Road noise is something that most people notice first. Tyres with a tread pattern designed for off-road use for example, will make more noise as air is trapped and squeezed in pockets between the road surface and gaps in the heavy tread pattern. Severely worn tyres won’t grip the road sufficiently so a properly matched tyre in good condition is ideal.

Air pressure: Too flat – you’ll use more petrol as the rolling resistance increases. Too high – you’ll lose traction. Solution – always follow the manufacturer’s guidelines and purchase good quality options. ‘Buy nice or pay twice’.

Wheel Replacement

rx7 with dish rims

You’ve no doubt noticed that many drivers replace their OEM (Original Equipment Manufacturer) wheels with aftermarket wheels. Naturally, there’s a huge market and enormous range of choices for different car wheels. People usually replace OEM wheels for looks, but also to fit wider tyres or clear upgraded brakes – a wide rim is able to house larger brakes.

Effects of Changing Wheels

ratchet on wheel nut

Other than looks, there are more things to be aware of when replacing OEM car wheels.

Stud pattern – (bolt pattern) The bolts that hold the wheel onto your car. Most are 4 or 5 stud but have different ‘patterns’.  The PCD (Pitch Circle Diameter) is the diameter of an imaginary circle drawn around the centers of the studs. For example, a 5×100 pattern has 5 studs placed in a circle with a diameter of 100mm. You’ll need to select the correct fitting rim if you replace the OEM car wheels.

Speedometer – Most cars calculate speed by measuring the time a wheel takes to turn around. The shorter the time car wheels take to complete one rotation, the faster the car is travelling. Increasing or decreasing the diameter of a wheel can cause cars to miscalculate those rotation times, resulting in incorrect speed readings.

Width – Increasing the width of car wheels is a popular option for some car owners. Known as ‘dish rims’ and popular in the Japanese motorsport scene, they allow wider tyres and larger brakes. On the downside, wider car wheels can interfere with the body or a car and cause tyres to scrub or rub against the guards in certain driving conditions. This is when guard rolling may be required to ‘bend’ guard out of the way.

The low down

under a car view

Maintaining your wheels and tyres is, of course, a good idea. A comfortable and safe drive is what the whole automotive industry is aiming for. Checking your tyre pressure is free and easy. Almost all petrol stations in Australia provide a free-to-use air pump. Simply undo the valve caps, attach the nozzle and make sure they’re inflated correctly. The manufacturer specifications are on your car’s tyre placard and owner’s manual.

When choosing aftermarket wheels, it’s worth talking to a professional to make sure they fit safely and provide correct speed readings.

Knowing how to drive on Australian highways and drive safely at night is important.

Check out these other safety features to make sure you and your family are as safe as possible on the road.

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