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Tyre Pressure

Tyre Myths: Do Tyre Pressure Monitoring Systems Tell You When You Need to Change Your Tyres?

Modern Sensors Make Driving a Breeze

Modern cars make driving a lot easier with all the things they do for us. You no longer need to turn your headlights on when it’s dark, or your windscreen wipers when it rains. You are warned when you drive over the speed limit. They may even tell you what your tyre pressure is. But do modern sensors know how to warn you when your tyres need changing?

What are Tyre Pressure Monitoring Systems (TPMSs)?

A Tyre Pressure Monitoring System does exactly what it says on the tin. It is an electronic system installed on your car to monitor the air pressure in your tyres.

Modern cars (typically from 2008 onwards) often come with a TPMS installed. The systems use sensors to continuously monitor the pressure of the air in your tyres. A warning light on your dashboard signals when your tyre pressure becomes dangerously low. This warning is a safety feature to prevent you from driving on dangerous tyres. The TPMS can also help you improve the longevity of your tyres by maintaining the correct PSI.

How Do TPMSs work?

Not all TPMSs are the same. The low tyre pressure warning light on your dashboard is the last step for an indirect TPMS or a direct TPMS.

·      Indirect TPMS

An indirect TPMS uses wheel speed to calculate pressure. Rather than measure the pressure in the tyre, the system uses wheel speed sensors from the antilock brakes. Based on the speed of each tyre, an onboard calculator works out the amount of revolutions a tyre is doing. The number is interpreted to figure out the pressure of the tyres, with underinflated tyres spinning faster than they would at correct inflation.

·      Direct TPMS

A direct TPMS uses pressure sensors in the wheel to calculate the PSI. A direct TPMS is more reliable than indirect, as you get a specific tyre pressure reading rather than an interpretation. Measurements from the direct TPMS are analysed by an onboard computer, and, if the pressure is lower than recommended, a warning light will flash on your dashboard.

Data from sensors is sent wirelessly to the onboard computer. To ensure that your tyre pressure is not from another vehicle, each system has its own unique serial number.

When Do You Need to Change Your Tyres?

A TPMS is great for warning you when you need to inflate your tyres. However, there are no sensors to warn you about tread wear or other hazards that mean you need to change your tyres. Instead, you should include a tyre inspection as part of your regular tyre maintenance routine. Here are some examples of signs that you need to change your tyres:

  • Tread depth gets too low: The legal minimum tread depth in Australia is 1.5mm. Tread depth has an impact on stopping distance, and some vehicle manufacturers argue that minimum tread depth should be legally increased to 2mm or 3mm.
  • Uneven tyre wear: Uneven wear is an indication of unusual stress on a tyre. Causes include incorrect wheel alignments or the wrong air pressure in your tyres.
  • Tyre age: You may use your vehicle infrequently and not put a lot of wear on your tyres. However, vehicle and tyre manufacturers still recommend you change your tyres regularly. Tyres over five years old dry out, losing elasticity and becoming increasingly dangerous to use.

What Do the Experts Have to Say?

Vehicle and tyre manufacturers have often worked together in creating TPMSs. They will both agree that they are helpful tools and useful for maintaining safe air pressure in your tyres. However, they also agree that while the systems are useful, they cannot warn you when you need fresh tyres.

For example, Bridgestone says:

“Tyre Pressure Monitoring Systems are only able to keep track of the amount of pressure within a tyre. They do not indicate whether a tyre has worn out its tread or the right time to replace it.”

If your TPMS continually signals a warning, you should get your tyre checked by a professional. Feel free to contact us to book an appointment or ask any questions you may have.

Keeping your family and fleet safe on the road,

Dean Wood

Tyre Pressure

Get a Grip: Is Letting Air Out of Your Tyres to Improve Control a Myth?

What’s the Relationship Between Air Pressure and Traction?

The pressure of your vehicle’s tyres sets the weight distribution across the tread pattern. With the manufacturer’s recommended tyre pressure (often found on the tyre placard in the driver’s side door jamb), your vehicle is most stable.

When a tyre is not correctly inflated, it loses its stability. In turn, this affects your handling, cornering, and stopping distance. Incorrect tyre pressure also causes tyres to wear unevenly, meaning they need replacing more frequently.

From the type of wear on your tyres, we can tell whether you underinflate or overinflate:

  • More wear in the centre of the tread means your tyres are overinflated
  • More wear on the outer edges means your tyres are underinflated

Tyres lose traction when the shape of the tyre becomes deformed and the tread becomes uneven.

Here’s a table that explains the increases and reductions in factors as a result of tyre pressure:

Under Pressure Recommended Pressure Over Pressure
– Performance + Performance – Traction
– Safety + Safety – Safety
– Response + Even Wear + Tyre Damage

Does Letting Air Out of Your Tyres Improve Grip?

You may have heard that letting some air out of your tyres improves grip. The logic is that the more of the tyre touching the ground, the better the traction. Though friction is what grips your tyre to the road, it does not depend on the surface area.

There’s an equation to measure friction. The pressure on your tyres is equal to the force divided by the area of contact. Therefore, an increase in the surface area of your tyre touching the road due to deflation is counteracted by the reduced pressure. The friction (and therefore traction) doesn’t increase.

Though your underinflated tyre will have no effect on your tyre’s traction, it will have a negative effect on your steering and stopping distances. You don’t want this in normal conditions, never mind on a slippery road.

What Can You Do to Improve the Grip of Your Tyres in Slippery Conditions?

In Australia, there are 5.4 road-related deaths per 100,000 people each year. Most of these are single-vehicle accidents rather than collisions. After long periods of hot and dry weather that are broken by heavy rainfall, the roads become extremely dangerous. When you take your car out in these conditions, you may as well be driving on an ice rink. So, what can you do to stay safe and improve tyre grip on the roads?

Drive Safely

The number one thing you can do to stay safe in slippery conditions is to be a sensible driver. Always maintain your tyres in good condition, ensure they are correctly inflated, and:

  • Increase the distance between yourself and other vehicles
  • Make gentle turns and slow down for a corner
  • Don’t brake if the vehicle aquaplanes; instead, pull off the accelerator and concentrate on steering through

What Causes Tyres to Lose Grip?

Tyres lose grip on the road due to a lack of traction. Here are some reasons your tyres might lose traction:

  • Overbraking: By braking too hard, you can cause your wheels to lock up
  • Oversteering: By steering too hard, you can cause the back end of your vehicle to slide out
  • Over-acceleration: Applying too much power when accelerating leads to wheel spin
  • Speeding: Driving too fast in slippery conditions causes a lack of traction

What Do the Experts Have to Say?

Tyre and vehicle manufacturers will all tell you the same thing when it comes to letting the air out of your tyres to improve grip. Bridgestone’s advice is:

“Underinflated tyres do not provide better contact with the road. Plus, it increases the amount of wear and tear to not only the bottom but also the shoulder of the tyres.

Do your tyres keep deflating? Have you noticed uneven tread wear? Feel free to contact us to book an appointment or ask any questions you may have.

Keeping your family and fleet safe on the road,

Dean Wood

TYre Pressure

Pump up the Pressure – and Explode Your Tyres?

Is it a tyre myth that overinflation can burst tyres?

It’s easy to think of tyres like balloons; we’ve all burst one of those because we overinflated it. But will overinflation cause your tyre to burst? It’s one of the most common tyre myths. It’s time we explored it.

What is the correct tyre pressure?

The right tyre pressure for your tyres depends upon your vehicle. You’ll find the recommended tyre pressure on the tyre placard on the door jamb or in your vehicle’s owner’s manual. It’s not the tyre pressure on the sidewall – that is the maximum tyre pressure at maximum load.

Will overinflation increase the risk of a blowout?

If you overinflate your tyres and drive at speed, and hit a pothole or other debris, there is a risk that you could suffer a blowout. But that risk is very slim. If it does happen, it’s more likely to be because of an existing fault in the tyre.

The pressure at which a tyre burst is around 200 PSI. This is around 165 PSI higher than the average recommended tyre inflation pressure. You really would have to pump some air into a tyre to get its pressure up there.

So, is it safe to overinflate a tyre?

It’s certainly safer than underinflating a tyre, but you still wouldn’t want to overinflate your tyres.

When a tyre is overinflated, the tyre’s walls push out. The tyre becomes stiffer than it should be. This affects performance. Traction is likely to be reduced, as there is less rubber on the road. This also means that tyre wear will be concentrated along the centre of the tyre, with the likelihood of bald patches caused by hard braking.

You may also suffer increased fuel consumption because the engine must work harder to drive the vehicle forward on reduced traction. You are like to have a bouncier, more unstable and less comfortable ride. Tyre sidewalls act as second shock absorbers, softening the blow to your car’s actual shock absorbers. When you overinflate a tyre, the sidewall’s stiffness transfers directly to the shock suspension.

So, is it better to underinflate a tyre?

No! It’s more dangerous to put too little air in a tyre than too much. Underinflation puts stress on a tyre’s shoulders and sidewalls. The stress on the tyre’s steel belts can be enormous. With the temperature reaching as high as 200 degrees in this spot, the chances of tyre failure are massively increased.

When you underinflate tyres, you are likely to increase fuel consumption and increase wear and tear. You will need to renew your tyres sooner. But the big danger is the increased risk of catastrophic failure.

What the experts say

Unless you have a death wish or your tyres are defective, you won’t overinflate your tyres to bursting point. They are more robust than party balloons. However, overinflated tyres may be more at risk of bursting if you hit potholes, kerbs, or other debris at speed. Still, underinflated tyres are more dangerous.

Bridgestone says:

Your tyres will not explode simply by overinflating them. (However) overinflation will cause unnecessarily excessive wear on the tyre and reduce the amount of contact with the road. It will also cause drivers to assume that their vehicles are more responsive due to the reduced contact resistance between tyre and road.

Having said all this, you should ensure that you don’t inflate your tyres to more than the tyre manufacturer’s recommended maximum (as displayed on the tyre sidewall). Further, you should always inflate to your vehicle manufacturer’s recommended tyre pressure, found on the door jamb and/or vehicle owner’s manual.

Not sure what tyre pressure is right for your vehicle? Feel free to contact us to book an appointment or ask any questions you may have.

Keeping your family and fleet safe on the road,

Dean Wood

Tyre Pressure

Don’t Put Your Tyres Under Pressure – Inflate Them Correctly

Don’t Put Your Tyres Under Pressure – Inflate Them Correctly

The need for proper inflation isn’t simply hot air

We’ve all done it – gone to inflate our tyres and forgotten what the tyre pressure should be. I’ve lost count of the number of times I’ve seen a motorist searching for the recommended tyre pressure on the tyre wall. Because they believe, like so many others do, that ‘the correct tyre pressure is numbered on the tyre’.

What is tyre pressure?

Tyre pressure is a measurement of how much air there is in a tyre. It is usually measured in pounds per square inch (PSI), though can also be measured in Bars.

Why must your tyres be inflated to the correct pressure?

If you don’t inflate your tyres properly, your comfort and safety will suffer. So, too, will your tyre wear and tear.

Underinflate your tyres and there will be more rubber against the road. Your tyres will wear faster across the tread. Tyre walls may crack easier. Especially in the summer, your tyre will heat up faster. More tread against the tarmac means more friction. This means you will use more fuel.

Should you overinflate your tyres, less of the tyre will be in contact with the road. This leads to more wear along the centre of the tyre as well as a bouncier driving experience. You may find your tyre suffers bald patches. Also, your braking distance will be longer.

Both overinflated and underinflated tyres are more prone to tyre blowouts. And you know how dangerous that can be – especially at speed.

What pressure should you inflate your tyres to?

The tyre pressure embossed on the sidewall of a tyre is not a recommended pressure. It is the absolute maximum pressure at which the tyre will operate effectively with a maximum load. When buying tyres for your vehicle, you should compare this number with your vehicle manufacturer’s recommended tyre pressure. You will find your vehicle’s tyre pressure guide in one or both of the following places:

  • On the door jamb
  • In the owner’s manual

If the maximum tyre pressure on the sidewall of a tyre is below your vehicle manufacturer’s recommended tyre pressure, you should buy a different tyre.

Checking your tyre pressure

You should check your tyre pressure regularly; at least every month, and if there is a sudden change in temperature. The easiest way to do so is at a nearby tyre station. Remember that tyre pressures should always be checked when the tyre is cold. Follow these five steps to check and inflate your tyres correctly:

  1. If you have driven more than a couple of kilometres, sit with a coffee for 10 minutes before checking your tyre pressure
  2. Set the air compressor to the lowest number on your tyre pressure guide (this is the recommended pressure for cold tyres)
  3. Remove the valve cap from your tyre’s valve stem, then connect the pressure gauge (no hissing)
  4. Inflate to the set pressure and replace the valve cap
  5. Repeat for all tyres

What the experts say

It is essential that you inflate your tyres correctly. You will reduce wear and your tyres will last longer, reducing your tyre costs over the longer term. You’ll find you consume less fuel. Your drive will be more comfortable, and your handling will be surer with better braking. Taking five minutes at least once a month to check that your tyres are inflated correctly will save you money, and could save your life. Bridgestone says:

Tyres must be inflated according to the vehicle manufacturers’ recommendations. Consult your vehicle manual or tyre pressure information sticker.

Even here in Brisbane, when the temperature falls your tyre pressure will fall. If we’ve had a belter of summer followed by a sudden drop in temperature, your tyre pressures could be off by 5% to 10% of the recommended PSI.

Whether summer or winter, make sure you check tyre pressures regularly as part of your vehicle inspection routine.

Do your tyres keep losing pressure? Feel free to contact us to book an appointment or ask any questions you may have.

Keeping your family and fleet safe on the road,

Dean Wood

Where is the best tyre pressure guide for your car?

Best Tyre Pressure Guides are for you car and driving conditions not the tyre.

When I discussed the risks of getting your tyre pressure check wrong in my last post, I pointed out that most people make the mistake of looking at the numbers on the tyres when checking what tyre pressure they need to inflate to (rather than the cars tyre pressure guide). The tyre number is the tyre manufacturer’s recommended maximum for that particular tyre. The best tyre pressure that you should use will most likely be lower than this.

In this post, I’ll explain where to find the tyre pressure guide for your car,  and how to make sure your tyres are always inflated correctly.

What it the best tyre pressure for your car?

The majority of cars have a tyre pressure guide label on the inside of the driver’s door frame – commonly on the pillar. Sometimes you’ll find this label on the side of the glove compartment or the glove compartment door. Some manufacturers ‘hide’ it on the inside of the fuel filler door.

If you can’t find the pressure guide in any of these places, then you’ll need to refer to the owner’s manual, which came with the car.

You can check your tyre pressure with a good pressure gauge. Generally, the more you spend on a gauge, the more accurate it will be. However, you don’t have to spend any money on fancy tools and instruments to make sure your tyre pressure is right.

The easy way to check tyre pressure

Take your car to the nearest petrol station with an air station, and follow these steps:

  1. Make sure your tyres are cold. Heat expands the air in a tyre, so ideally you shouldn’t have driven more than a couple of kilometres before checking tyre pressure. If you’ve driven further than this, have a coffee, read a newspaper, or take a ten-minute stroll.
  2. Locate the lowest number on your tyre pressure guide. This is the cold tyre pressure recommended by the car manufacturer.
  3. Set the air compressor to the manufacturer’s recommended pressure. You’ll be able to either read your tyre pressure or inflate the tyre to the pressure you’ve set.
  4. Unscrew the valve cap from the stem on the tyre, and connect the air pressure gauge to the tyre valve. If it hisses, the gauge isn’t plugged in correctly.
  5. Check the pressure reading is the same as the manufacturer’s recommended pressure. If it isn’t, inflate to the right pressure. Replace the valve cap.
  6. Repeat for all tyres on your car.

Factors that make a difference to tyre pressure

In hot weather, tyre pressures rise, while in cold weather they fall. So it’s especially important to check your tyre pressure when the weather changes.

If you’re carrying an extra heavy load, you may need to inflate to higher than the recommended pressure – but never exceed the maximum PSI on the tyre sidewall.

Never make a judgment about tyre pressure by just looking at the tyres. Modern tyres can be deceptive, and often look underinflated when they’re not.

A word or warning about pressure gauges at petrol stations

It’s always best to spend a few dollars on an accurate pressure gauge. Petrol station air pumps are free, but they suffer a lot of abuse, and may not be calibrated accurately. So use the above method to check tyre pressure, but understand that your tyres might still be inflated to the wrong PSI.

If you have any doubts about the correct pressure for your tyres, or if you might have a slow leak, call into our tyre shop, or contact us on 3375 3566 to put your mind at rest.

Keeping your family and fleet safely on the road,

Kevin Wood

Tyre Centre Tips – The risks of getting your tyre pressure check wrong

Tyre Centre Tips – Tyre Pressure, a couple of minutes each month could save your life and your pocket.

One of the common mistakes made by drivers is to inflate their tyres wrongly. When you do this, you risk your safety and comfort.  In this post, I’ll explain what could happen when you either over inflate or under inflate your tyre pressure. The Darra tyre centre experts will show you how most people get their tyre pressure check wrong, and why so many tyres ‘leak’ air.

What is tyre pressure?

Tyre pressure is the way that you measure how much air is in your car’s tyres. It’s measured in pounds per square inch (PSI), and you should check the pressures of all your tyres at least once a month.

If you don’t have the right tyre pressures, your driving will be compromised. In fact, I’d go as far as saying that your tyres are probably the second most important safety device on your car – second only to your brakes. You can save your life by proper tyre rotation, but only if they are properly inflated, too.

What could happen if your tyres aren’t properly inflated?

Improperly inflated tyres make for a less comfortable journey. You’ll bounce around a lot more, cornering will be compromised, and braking ability will be reduced. You could also find that your wheel alignment is knocked out of position.

In the worst case, it’s possible that your tyre could blow – most likely while travelling at high speed. If you’re lucky, the worst that will happen is reduced tyre life and a few less kilometres per litre of fuel.

What happens if you overinflate your tyres?

When your tyre pressure is too high, less of the tyre will be in contact with the road. Your drive will feel more bouncy. Because there is less contact on the road, your braking suffers. Wear will be uneven, causing bald patches and increases the risk of an accident.

What happens if you underinflate your tyres?

If you don’t have enough air in your tyres, there will be more rubber against the tarmac. Road friction will increase, and your tyres will degrade faster. Because of the extra friction, you’ll use more fuel.

With more of your tyre in contact with the road, overheating becomes a problem – especially in the summer months and on motorways. While blowouts don’t happen often, when they do, low pressure is a common factor.

If your tyres squeal when you are driving round corners, the chances are that your tyre pressure is low.

If your tyres appear to leak, should you be worried?

Tyres naturally lose air (pressure) over time. This is most likely due to temperature changes. According to the experts at Goodyear, every 10 degrees drop in temperature causes a fall of one to two pounds of pressure.

If the temperature hasn’t fallen and your tyres appear to be a little on the flat side, it doesn’t necessarily mean that they have a leak. It could be that air is leaking through the valve stem or where the tyre is in contact with the wheel. The safe thing to do is to get your tyres and wheels checked if you suspect you’ve got a leak.

Why most people get their tyre pressure wrong

Most people drive around with incorrectly inflated tyres. That’s because they make the most common mistake that drivers make. Instead of inflating to the recommended pressure, they look at the markings on the tyre and inflate to that pressure. These markings simply tell you the maximum that the tyre can be inflated to − not the best pressure for your car and model.

If you look on the inside of your door frame, you should find a label which details recommended tyre pressures. If it’s not there, get the car manual out and check before inflating.

Stay safe and cut your driving costs

Correctly inflated tyres reduce wear on the tread. Your tyres will last a few months longer. Your fuel economy will rise. Most importantly, your drive will be more stable, cornering will be smoother, and braking more responsive.

In the winter months, your tyre pressure will naturally fall as the temperature falls. You may find that you need to put more air into your tyres as the days get shorter. If we’ve had a particularly hot summer here in Brisbane and it’s followed by a freezing winter, your tyre pressure could be off by five or six PSI.

Make sure you check air pressure regularly as part of your vehicle inspection routine.

If you have any doubts about the correct pressure for your tyres, or if you might have a slow leak, call into our tyre shop, or contact us on 3375 3566 to get the answers to your questions.

Keeping your family and fleet safely on the road,

Kevin Wood


New Tyre Size – Square Tyres, What will Pommys Think of Next?

6,000 miles on a flat

I’m guessing when the Pommies say “It could only happen in America” they don’t think about any of the strange events in Britain, like an airplane landing on a square tyre. That’s exactly what happened a couple of weeks ago at Heathrow when an Airbus A380 flying from Hong Kong landed at Britain’s busiest airport after suffering a loss of tyre pressure in Hong Kong.

Here at Darra we thought we had worked with every tyre going. But we guarantee we’ve never seen a square tyre. Whatever vehicle we’ve fitted with tyres – be it crane tyres, earthmover tyres, commercial tyres, fleet tyres, and so on – we have never, ever, not once, fitted a square tyre.

So what did happen to the A380 tyre?

The pilot received a loss of pressure warning as he was taking off from Hong Kong, but chose to ignore it. (That’s either a very brave call, in which case he must have been an Aussie pilot. Or a very dumb call, in which case the British Airways pilot might very well have been Pom, I guess!)

One airline pilot ventured that the tyre may have detached from the wheel on landing. He said, “The tyres are pressurised to around seven times that of a car tyre. Once depressurised the tyre will have ‘flatted’ while the aircraft was braking and once it did so it would then rotate through 90 degrees to another part of the tyre and then do it again — hence the four flats you see.”

A Civil Aviation Authority (CAA)  spokesperson said that it had never seen anything like it before. However, the CAA and other pilots didn’t seem overly concerned about the problem square tyre. One even said, “Is it dangerous? No. To lose one is no big deal.”

Don’t risk loss of tyre pressure on the road and never try out this new tyre size!

Though the thoughts of the CAA and other pilots might seem nonchalant, you can kind of see their point: the plane did have 17 other tyres to rely on. Having said that, we wouldn’t suggest that you risk having a loss of tyre pressure. Most road vehicles only have three other tyres to carry them through a journey safely, losing one is going to be mighty dangerous.

If you’ve ever seen a square tyre before, we’d love to hear about it. Meanwhile, stay safe and have your tyres checked regularly. Give us a call today on 3333 5510 to guarantee you don’t suffer a Pommy blow out. We’d rather you use our mobile service than be caught out while you’re working or travelling.

Keeping your family and fleet safely on the road,

The team at Darra Tyres.