Braking distances and tread depths

Posted by: Dan on 28/08/2012

Category: Tyre Information

What’s the tread depth of your tyres? You almost certainly don’t know the answer to this question, and honestly, I can’t blame you for not knowing. It’s not the kind of detail that’s at the forefront of most 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 is not that complicated and is a great way to measure how worn out your tyres are. So here are the 3 basic figures you need to know about tread depth on your tyres in Australia:

  1. 8.0mm – this is the tread depth on new tyres
  2. 3.0mm – this is the tread depth at which we recommend you look for new tyres
  3. 1.6mm – this is the minimum legal tread depth allowed on your tyres and at this point you MUST replace your tyres

Obviously your next question is “why does Tyreright recommend getting new tyres at almost double the minimum legal tread depth?” and I’m sure that there’s more than one cynic who thinks it’s just because we’re trying to sell more tyres. Honestly, that’s not the case. The truth is that tread depth makes a big difference to your handling, cornering and most importantly, to your stopping ability.

This is especially true in wet conditions. Consider the image below*:

At 80km/h stopping distance in the wet can vary significantly based on the amount of tread on your tyres

Travelling at 80km/h in the wet you see a hazard in the road and need to stop quickly. On a new tyre this is achieved comfortably and with reduced risk of aquaplaning. On a tyre that has been worn down to 3.0mm in tread depth the same car will still be travelling in excess of 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 in excess of 40km/h when the car on 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 will 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 like a Holden Commodore or Ford Falcon is about 5m in length, then it’s nearly two full car-lengths needed to stop with 3mm tread depth and just over 3 and a half car-lengths needed to stop with 1.6mm tread depth.

If you’d like to know more about to measure your tread depth or about maintaining your tyres so that you’re safe on the road feel free to call into one of our stores for a free tyre safety check, call us on 138 168 or use our live chat feature on the website to speak with one of our staff today.

*test referenced in this article was braking from 80km/h to a standstill in the wet using a Mercedes C-Class with 205/55R16 tyres in over 1000 braking tests. Please note that braking distances will vary depending on vehicle, tyres, brakes, road surface and other conditions.