Rules on tyre change so you don’t compromise your on-road safety
Most cars are now front-wheel drive. This means that most of the work is performed ahead of you, across your front axle. On a front-wheel-drive vehicle, your front tyres usually suffer more tread wear than your rear tyres. This gives birth to the myth that ‘you only need to change the front tyres’.
What is a front-wheel-drive?
On a front-wheel-drive vehicle, all the hard work is done at the front. Traction. Steering. Cornering. Most of the braking. The bulk of the weight of the car is at the front, too. This is where the engine is. All this stress is placed on your vehicle’s front tyres. Thus, they wear faster than the rear tyres.
Why do people think you only need to change the front tyres on a front-wheel drive?
If it is your front tyres that are worn most, it’s an unnecessary expense to replace all four tyres. It’s the tread on the front tyres that is near the legal limit. Why waste two perfectly good tyres on the rear axle? Plus, the tyres at the front will wear the fastest. It makes sense to replace the front tyres, doesn’t it?
Why it isn’t safe to change the front tyres only
When you consider how a vehicle handles, there are usually three states when you corner. These are neutral steer, oversteer, and understeer. When you understand what causes these three steering states, you’ll understand why changing only the front tyres is a big mistake.
· Neutral steer
When this happens, the front of your vehicle follows the path you are steering. You stay on the exact line you intend.
When you corner with oversteer, your vehicle follows a tighter line than you intend. This is caused by a lack of grip on the rear axle.
The front slides a little wider than you intend.
Now, consider the vehicle you are driving. It is front-loaded, not just because it is front-wheel drive. All that weight and most of the moving parts, such as your transmission, are at the front of the vehicle. This makes it difficult to manufacture a neutral steer vehicle.
When you oversteer, you must reduce your steering angle. This is opposite of what your natural reaction will be. Naturally, you will either:
- Brake hard, which transfers load away from the rear axle and reduces grip at the rear; or
- Take your foot off the accelerator, which transfers weight to the front axle and reduces grip at the rear
It is much harder to control an oversteering vehicle than an understeering vehicle. So, manufacturers design vehicles to deliberately understeer.
As you can see, though most of the work is done at the front of a front-wheel drive vehicle, it’s better to have the grip at the back than the front.
What the experts say
A good driving style and good tyre maintenance regime will help to keep your tyres in good condition. As part of your tyre maintenance, you should rotate your tyres every 10,000 kilometres. This will ensure that your tyres wear evenly across both axles.
It is always best to change all four tyres at the same time. However, the rear tyres may not need replacing. If this is the case, you may not wish to replace all four tyres (it’s more expensive and wasteful, who would?). In this case, you should move your existing rear tyres to the front axle and put the new tyres on the rear axle. As Bridgestone says:
“You should change all four tyres at the same time to maintain even tread wear. It is also recommended to rotate your tyres every 10,000km to ensure they wear out evenly.”
Most motorists don’t rotate tyres. Most also put new tyres on the front axle when their front tyres need replacing. That’s a mistake. Don’t make it. Have the tyre shop switch your rear tyres to the front, and set the new tyres on the rear axle.
Are your tyres near their sell-by date? Feel free to contact us to book an appointment or ask any questions you may have.
Keeping your family and fleet safe on the road,