4WD versus AWD, what are the functional differences?

Subaru Symmetrical All Wheel Drive is one of the most well known AWD platforms.

What’s the difference between AWD and 4WD?

Whether you’re shopping for a new car or looking to understand your current vehicle better, you may have heard lots of terms, acronyms and codes being thrown around.

This blog post is going to help you out when you’re looking for information about the terms ’All wheel drive’ or ‘four wheel drive’ and want to understand what the differences are.

Here’s a detailed breakdown to help you understand different vehicle drivetrains, their advantages, and how they relate to tyre care.

What is meant by 'Drive'?

When talking about passenger vehicles, ‘drive’ refers to which wheels receive power to propel the car forward. It doesn’t matter whether that power comes from a petrol or diesel internal combustion engine, an electric motor, or even a combination of both.

Whether the driving forces are sent to the front wheels, rear wheels, or a combination of both have implications in terms of influencing handling, efficiency and capability. Before we dive into the AWD vs 4WD question, what are the more traditional drivetrain layouts?

Rear-Wheel Drive (RWD)

Common amongst utility vehicles and sports cars alike, rear wheel drive drivetrains send their power exclusively to the rear wheels. This offers a better front to rear weight balance and handling in high performance conditions.

Many commercial vehicles are rear wheel drive as a practical choice. Ensuring that the driven wheels are under where the payload is helps with traction in slippery conditions.

Front-Wheel Drive (FWD)

Found on most passenger vehicles, smaller vehicles and economy-oriented cars, a front wheel drivetrain directs all the power to the front wheels. This is generally great for efficiency, and the smaller size is more practical to fit in a variety of vehicles.

All-Wheel Drive (AWD)

Picture just about any Subaru and that’s going to be the best example of AWD that most people know. Some AWD drivetrains favour the front of rear axle for torque output or can vary the percentage of torque sent to each end of the car depending on conditions based on computer control and an electronic or hydraulic centre differential.

While some AWD systems can reach an even 50:50 torque split front to rear, the degree and duration that AWD systems can do this is often heavily restricted compared to 4WD drivetrains.

AWD drivetrains are ideal for on-road driving and mild offroad conditions such as wet grass, gravel, snow and ice. AWD vehicles don’t allow drivers to ‘disengage’ parts of the drivetrain when they’re not required.

Pros:

• Improved traction in varied weather conditions, compared to FWD or RWD.
• Better handling and acceleration for mid-corner or low grip situations.

Cons:

• Higher fuel consumption than FWD or RWD.
• Can be more complex and expensive to maintain.

Even though 4x4 or 4wd can be used to label whole vehicles, the name relates to drivetrain type.

Four-Wheel Drive (4WD)

4WD and AWD share similarities in that engine power can be distributed to both front and rear wheels, however, 4WD systems allow the driver to switch between drivetrain settings through a mechanically operated differential.

Many 4WD vehicles can operate in rear wheel drive-only most of the time, and allow the front wheel to be engaged only when required. It is also possible to mechanically lock the centre differential or transfer case in order to send up to 50% of the engine torque to the front and rear wheels almost without limitation. This can be extremely useful off road, and is the main point of difference between 4WD and AWD systems.

You’ll find 4WD drivetrains most commonly in larger SUVs and trucks like the Toyota Landcruiser, Ford Rangers, Tritons, Navara's and other similar vehicles.

4WD drivetrains are preferred for severe off-road activities such as rock crawling, sand, mud and more extreme conditions thanks to their ability to be activated to best suit the current conditions.

Pros:

• Switchable drivetrain modes.
• Ability to lock front and rear axles together through mechanical means.

Cons:

• Generally poorer fuel economy.
• 4WD drivetrains are heavier and often less comfortable for everyday driving.

Choosing the Right Drivetrain

When it comes to off-road use, 4WD is undoubtedly the better choice for serious off-road driving. Thanks to their more robust construction and selectable drive modes, they’re often able to be used more efficiently, based on what the driver needs at the time.

If you’re sticking on road, AWD systems are more suitable for general use in varying weather conditions. The functions of an AWD system are more transparent to the driver and will react to what’s happening on the road.

What Different Drivetrains Mean to Tyres

The type of drivetrain in your vehicle will heavily influence how your tyres wear out over time.

For example, in a front wheel drive car, the front tyres are responsible for all of the acceleration forces, all of the steering forces and most of the brake forces, while the rear wheels are simply holding the back of the car off the ground. Rear wheel drive vehicles put all their acceleration forces into their rear wheels, while the fronts still handle most of the braking and steering forces.

This is grossly simplified, but a great example of how drivetrains can affect tyre wear, and how tyre rotations can help spread different types of wear around, ensuring that your tyres last as long as possible.

AWD and 4WD vehicles spread their tyre wear out a lot more evenly than FWD vehicles do, but this doesn’t mean that routine tyre inspections should be glossed over. Due to the complex nature of most AWD systems and their hydraulically controlled differentials, they are much more sensitive to premature tyre wear and mismatched tyre sizes. This is why many manufacturers recommend changing tyres in pairs or in sets, should a tyre require a replacement.

Due to their mechanical nature, many 4WD drivetrains are more resilient to tyre size differences. It’s always best to consult your owners manual for specific advice on tyre rotation schedules as well as permissible tyre replacement procedures.

Your Local Specialists

Regardless of what vehicle you drive, your local Tyrepower store can help you out. With over 55 locations in Western Australia, you’re never far away from getting the power with Australias largest independent tyre retailer network.

With a wide range of vehicle data available to us, all the top brands, state of the art equipment and great customer service, Tyrepower should be your first call if you have any questions relating to your tyres and wheels.

Reach out to Tyrepower Wangara today by calling (08) 9409 7858 or by visiting our workshop, conveniently located at 18 Prindiville Drive, Wangara.