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Measuring tyre tread depth using a tool

Should I Change Tyres At 4mm? What About 3mm/2mm?

Are your car’s tyres due for a change?

When it comes to car maintenance, one question that often arises is whether you should change your tyres once they reach a certain tread depth

In Australia, the legal minimum tread depth is 1.5mm, but is that enough to ensure your safety on the road?

Why Tread Depth Matters

Tread depth plays a vital role in your tyres’ ability to grip the road.

As your tyres wear down, their ability to disperse water on wet surfaces diminishes, leading to a higher risk of hydroplaning.

In addition, tyres with adequate tread provide better traction and handling, especially in adverse weather conditions

Can You Still Drive With 4mm Tread?

The legal minimum tread depth in Australia is set at 1.5mm. This means that, by law, you must replace your tyres when the tread depth reaches this level.

However, this minimum requirement doesn’t necessarily mean your tyres are still safe for driving. Tread depth matters because it directly affects your tyres’ ability to maintain grip on the road.

At 4mm of tread depth, your tyres are still within the legal limit, but their performance may begin to decline.

In dry conditions and if your tyres are in good overall condition, you can often continue to drive safely. However, it’s essential to consider specific circumstances.

If you frequently drive in wet, icy, or slippery conditions, it’s advisable to replace your tyres earlier.

Should You Replace Tyres At 3mm?

Many experts recommend replacing your tyres when they reach approximately 3mm of tread depth. This recommendation stems from a focus on safety.

As tyres wear down, their ability to disperse water and maintain traction decreases. This is particularly noticeable in wet conditions.

When your tyres have 3mm of tread left, they still have a reasonable amount of grip on dry roads. However, in wet conditions, the risk of hydroplaning increases significantly.

Hydroplaning occurs when a layer of water builds up between the tyres and the road, leading to a loss of control.

To mitigate this risk, changing your tyres at 3mm is a prudent choice, especially if wet weather is common in your area.

What About 2mm Tread Depth?

As your tyres approach 2mm of tread depth, it’s strongly recommended to replace them. At this point, your tyres are no longer effective at maintaining grip in various road conditions.

The risk of hydroplaning in wet conditions becomes extremely high, and the overall safety of your vehicle is compromised.

Additionally, driving on tyres with 2mm of tread can also affect your car’s handling and braking performance. Stopping distances increase, which could lead to accidents or collisions.


Determining when to change your tyres in Australia varies depending on factors like legal requirements, expert advice, tyre and weather conditions, and personal preference.

Your foremost concern should always be road safety, so regularly inspect your tyres and monitor tread depth, so that you can make an informed decision.

Louis from Tyre Geek


I'm Louis, an engineer passionate about helping Australians choose better tyres for their vehicles!