Getting the best out of your tyres

18:10, Dec 22 2012
Kea chews on a tyre.
DON'T LEAVE IT TO THE BIRDS: Tyres need to be checked regularly.

When was the last time you checked your tyres?

As part of the AA's analysis of the Government's proposed changes to the Warrant of Fitness, the data on every fatal crash in New Zealand over five years from 2007-2011 was examined. The data showed that vehicle faults were a contributing factor in only a small number of crashes but, of these, tyre faults were far and away the majority.

It is a reminder to all of us that those four strips of rubber are absolutely crucial to keeping us safe on the road and every motorist should regularly take a few minutes to check their tyres are in the shape they need to be.

Think of it like rock climbing. If you were on a rock wall, you would want your four points of contact through your hands and feet to have as much grip as possible. When you are on the road you want to have the same through your tyres.


Just because your vehicle gets a warrant doesn't mean its tyres will be safe and legal until the next inspection.

A good vehicle inspection centre or garage will tell you that your tyres have only just passed or won't last much longer, but some may not let you know.

If your tread depth is close to the minimum threshold when you get your warrant, it could easily wear into the danger zone well before your next one.

Make it a habit to check your tyres yourself every month or two to make sure they are in good shape.


A tyre without enough tread can be as slippery as bowling shoes on a 10-pin lane. The grooves in the tread channel water away if the road is wet. If the tread gets too low, the tyre can't channel the water effectively and the vehicle is at risk of hydroplaning, where the wheels lose contact with the road and skid on top of a layer of water.

The legally required minimum tread depth to get a Warrant of Fitness is 1.5mm and you never want to go below this. Modern tyres will usually have a wear indicator (or wear bar) built into the tread. It's a section of the tread which is raised to indicate when the tyre is worn down to the minimum safe tread depth. When the wear bar is reached, the tyre is worn out. Some tyre companies have little hand-held gauges that people can use to check their tread depth or you can easily make one yourself by getting a matchstick or a small piece of cardboard and marking the bottom 2mm with a pen. You can then stick it into the grooves on your tyre and, if the mark is visible above the tread, it is time for a new tyre.


Your tyres will last longer, your car will handle better and you'll use less fuel if you keep your tyres at the correct pressure.

To check what pressure your tyres should be at, many cars have a sticker inside the frame of the driver's or passenger's door or it will be in the car manual if you have one.

AA tests have shown driving on incorrect tyre pressures can increase your fuel use by nearly 8 per cent so it is well worth taking a couple of minutes once a month to check them.


Cracks in the rubber or some of your tyres wearing out their tread faster in certain places are warning signs to watch for.

Even without being driven, tyres degrade over time and a tyre with cracks appearing indicates the surface is old and weakening. The best thing to do is replace it.

If the tread is worn down around the both edges but not in the middle it's a sign your tyres are consistently underinflated whereas if it's wearing in the middle faster than the edges then the tyre has been overinflated.

If there are patches or a strip on the tyre where the tread has worn away faster, then it indicates possible issues with the wheel's alignment or suspension and shock absorbers. The best thing to do is take it to your mechanic or tyre shop and get them to investigate.

If you can, it is well worth getting your wheels aligned, balanced and rotated as well. It will help them stay in top shape for longer.


Snow tyres are designed to operate in temperatures below 7 degrees C and unlike conventional tyres they must have a minimum of 4mm tread depth. It is illegal and unsafe to mix snow tyres with conventional tyres. However, snow tyres should not be confused with all-season ''mud and snow'' tyres (often marked with the letters 'M+S' on the sidewall), which are designed to perform safely in a wide range of summer and winter conditions and are commonly fitted to 4WD vehicles.