How to Buy Tyres

How to Save $300 - or more - on Tyres

Most people don't know this, but tread wear on your tyres accelerates dramatically when your tyres are under-inflated - even if those tyres are just a little bit under-inflated. One in four cars, statistically, has a dangerously under-inflated tyre - so there's a lot of potential cost-saving 'out there' on the road today.

This post is all about maintaining your tyres at the correct pressure: how to do it, what the correct pressures are, when to do it, and where.

WHAT YOU'LL SAVE

An average set of tyres will set you back about $600. (if you own a sporty car you'll be looking at more like $900-1000 a set, while a seriously sporty car like a Porsche might cost as much as $1000 per corner for a decent set of tyres.)

Tyres these days last about 40,000km. That's about three years of average driving. But, according to expert engineers, running with the pressure too low can easily double the wear rate - effectively halving the life of the tyres.

THE PROBLEM

Cars have become tremendously reliable in the past 30 years. It's hardly necessary for an owner to open the bonnet or perform other regular maintenance between services.

However, it's still very common for tyres to leak air gradually. This problem is compounded because modern radial tyres don't look significantly different if they are half flat - and they don't feel too different either, unless you swerve or brake hard. In this case (ie in an emergency) an under-inflated tyre can be a real safety liability.

Above: Low pressure is the leading cause of blowoutsUnder-inflation and high-speed running (typical long-distance highway driving) is the leading cause of blowouts. Running without enough air causes the sidewalls to flex too much - and too much flex = too much heat, resulting in catastrophic failure.

Fixing the problem is easy. It will certainly save you money ... And it might just save your neck.

THE SOLUTION: CORRECT PRESSURE

Theres a simple explanation to this, and a more complex one. Heres the simple one: 

Every car has a label with the correct tyre pressures specified by the car manufacturer. The label is called a tyre placard, and in the vast majority of cars it's inside the driver's door frame. (tyre placards are a regulatory thing - required by law.)

Above: A typical tyre placardJust look at the size of the tyres on the car (a code like 205/55R16 on the sidewall) and check what the recommended pressure is on the placard.

Get yourself down to the local service station for some free compressed air (one of the few things that is still free) and make all four tyres that pressure - then check them either every second time you fill the tank or every fortnight (whichever comes first) and most of your tyre wear problems will go away.

Bear in mind that the placard pressure is what's called a 'cold inflation pressure' so you're best doing the pressures before you've driven a significant distance.

Often the placard specifies two pressures, one for normal operation and one for highway use. If that's the case, go with 'highway'. (You might lose a little ride comfort, but you'll get the best possible handling and wear rate performance.)

If you can't find the tyre placard, 32-36psi is a good, safe operating pressure for average tyres.

The more complex explanation is that every car has an ideal set of pressures for it's operating conditions - ie the roads it's used on, the loads it's carrying and the way the car is driven.

To monitor the tyres more closely, look at the way the tread is wearing. Tyres that wear out on the outside edges are under-inflated and need to operate at a higher pressure (a common problem). You might want to add 10 or 15 per cent more air in this case. Tyres that wear out in the middle of the tread face are over-inflated (not so common).

If your tyres are wearing out on just one edge of the tread face (often the outside edge, especially a front tyre) then you probably need a wheel alignment. Mis-alignment of the front wheels is fairly common after you hit a pothole, kerb or speed hump.

Conclusion

Basically, you have two choices. Take control of tread wear and check those pressures once a fortnight like the owner's manual advises in most cars. Alternatively, be happy to contribute disproportionately to the profits of Bridgestone, Goodyear, Michelin, Pirelli, Hankook, Kumho, Dunlop and Continental, etc...