Braking distances and tread depths

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What’s the tread depth of your tyres? You probably don’t know the answer to this question – and, honestly, we can’t blame you for not knowing. It generally isn’t the kind of detail that’s at the forefront of our minds. That said, your tread depth is actually really important when it comes to the safety and performance of your tyres.

The truth is that tread depth isn’t that complicated and is a great way to measure how worn-out your tyres are. In Australia, the tread depth of new tyres is 8.0mm. It’s recommended you look for new tyres when the tread depth is 3.0mm. The minimum legal tread depth allowed on your tyres is 1.6mm and at this point you must replace your tyres.

You might be wondering why we recommend getting new tyres at almost double the minimum legal tread depth. Tread depth actually makes a big difference to your car’s handling, cornering and, most importantly, its stopping ability. This is especially true in wet conditions. Consider the image below*:

stopping distance brake tread

When travelling at 80km/h in the wet, you see a hazard in the road and need to stop quickly. On a new tyre, you’ll come to a stop comfortably and with reduced risk of aquaplaning. On a tyre that’s been worn down to 3.0mm in tread depth, the same car will still be travelling over 30km/h at the point the new tyre would have stopped, and will take an additional 9.5m to stop.

When driving on a tyre with the minimum legal tread depth of 1.6mm the same car will be travelling over 40km/h when the car with the new tyre has stopped and will still be in excess of 30km/h when the car with 3.0mm tread depth has stopped. It’ll take 18.6m more distance than the car on the new tyre to stop.

Another way to think of it is in car-lengths. If the average Australian sedan is about 5m in length, then it’s nearly two full car-lengths needed to stop with 3mm tread depth, and just over three-and-a-half car-lengths to stop with 1.6mm tread depth.

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*Test was braking from 80km/h to a standstill in the wet using a Mercedes-Benz C-Class with 205/55R16 tyres in over 1000 braking tests. Please note that braking distances will vary depending on the vehicle, tyres, brakes, road surface and other conditions.
**10% discount off the price for all tyres is available to NRMA members only for a limited time. The 10% discounted is calculated off the full invoice price excluding GST. Offer can only be redeemed via NRMA car servicing centres or NRMA mobile service in NSW. Offer is not transferable for cash. NRMA reserves the right to terminate this offer at our discretion. Standard NRMA car servicing terms and conditions apply, available at MotorServe Pty Ltd trading as NRMA Car Servicing ABN 41 121 715 393 license number MVRL43713