FACTS AND STATS

Tyre factors contributing to crashes, 2008 to 2012

# There can be more than one tyre factor associated with a crash so the rows may not add to the total.
Source: Ministry of Transport.

Tyres constantly lose pressure

Why? Tyres aren’t completely non-porous so lose air pressure naturally, by about 1-2psi per month. That’s why it’s recommended you check your tyre pressure monthly.

Underinflated tyres can reduce fuel efficiency by 4%

Why? When tyres are under-inflated, their rolling resistance increases. This means they need more energy or fuel to make them turn. Think about the different kicking performance of a rugby ball that is underinflated.

Underinflated tyres wear out faster

Why? When a tyre is under-inflated, its contact patch with the road surface is concentrated towards the two outer edges of the tread. This leads to rapid wear on the shoulders and reduced tyre life.

Over-inflation also causes uneven wear, as the contact patch is concentrated in the centre. It will also negatively affect your car’s handling abilities.

It takes longer to stop on wet roads if your tyres have less than 3mm tread

Why? A tyre is unable to deal with the same volume of water on the road at lower tread depths, which means that the tyre is unable to transmit traction and braking forces to the road as effectively. A new tyre usually has about 8mm of tread, and tests have shown that it’s at about 3mm that wet braking distance starts to significantly increase.

Did you know…?

• Tyres with a 3mm tread have a 25% better performance than those at 1.6mm in wet conditions
• Demanding driving conditions affect your tyres’ service life significantly – especially driving on rough roads or around urban and hilly areas a lot.
• Only around half of Kiwi drivers know the correct tyre pressure for their car
• Less than half of Kiwi drivers check their tyre pressure monthly
• If everyone in New Zealand kept their tyres correctly pumped, New Zealand would save enough fuel to fill 1,500 petrol tankers