Understanding Your Tyres

Understanding Your Tyres – Part 2

Understanding Your Tyres

In Part One of our Tyres blog, we gave you the heads up on some of the key reasons why caring for your tyres will save you money, and could save your life.

In Part Two, we cover four hotly debated tyre topics, including how cutting corners on replacement tyres could result in mechanical damage to your All Wheel Drive vehicle.

Punctures – Repair or Replacement Tyre?

Repair or Replace

Puncture repairs have increased in popularity over the last few years as the effectiveness of repair technology has improved. However, there are still very clear rules on whether a punctured tyre is repairable or not, and it’s always worth considering whether a repair is even worth it over simply replacing the tyre.

In most cases, the quickest and easiest way to deal with a puncture is to buy a new tyre and have 100% peace of mind. However, there are times when repairing a tyre could be an option.

Your tyre can be repaired if:

  • The puncture is smaller than 6mm.
  • A small object, such as a nail, has caused the puncture. This will cause a slow puncture, and while it may not seem serious it can lead to a blowout when driving at high speeds and needs to be addressed quickly.
  • In many cases, if the puncture is on the flat section of the tyre (where it has contact with the road) it can be repaired.   

If your motoring is mainly low-speed, short distance and close to home, a repair is worth considering as a short-term solution. 

It is not repairable if:

  • The puncture is larger than 6mm.
  • The puncture is deep. It is likely that the tyre could also be damaged on the inside. This can affect the tyre’s function and compromise the car’s safety. In this instance it is necessary to replace the tyre.
  • The tyre’s sidewall is punctured. Unlike the tread area, the sidewalls can’t be repaired. The sidewall is vital to the performance and structure of the tyre – any damage to this part of the tyre is a red flag and a replacement is required.
  • If the tyre is in generally poor condition, or is old, it is time to replace the tyre.

Ultimately, a new tyre will always provide a safer, longer-term solution to punctures, especially on today’s lower profile tyres.

Run Flat Tyres or Traditional Tyres?

Run Flat Tyres or Traditional Tyres?

A run flat tyre is a type of tyre that allows you to continue driving after suffering a puncture.

When a traditional tyre loses air due to a puncture, it collapses. As a result, the vehicle becomes immobile and you are forced to change the tyre on the spot or call a tow truck.

Run flat tyres on the other hand feature steel-reinforced sidewalls which allow for a deflated tyre to retain its shape without any air. This design allows the vehicle to be driven with reduced speed and for a limited distance until replacement of the tyre is possible.

If you are unsure whether your car is fitted with run flats, they can be easily identified by the symbols on the sidewall of the tyre.

Rather than a standardised code to represent run flat tyres – that would be too sensible! – most premium and mid-range tyre manufacturers have their own codes and symbols to indicate whether a tyre has run-flat capability. Common codes are ROF, RFT, RSC and ZP.

Advantages of Run Flat Tyres

  • No dangerous roadside tyre changes
  • No need to carry jacking equipment
  • The tyre stays on the rim when completely flat
  • Increased boot space (no need for a spare wheel and tyre)
  • Removing the weight of a spare wheel improves fuel economy

Disadvantages of Run Flat Tyres

  • Less choice of tyre sizes and tyre brands
  • More expensive than traditional tyres
  • Increased road noise
  • Harder ride due to stiffer side walls
  • Limited by speed and range (i.e. up to 80 km/h and 80 kms max distance)
  • The repair of a run flat tyre is not recommended under any circumstances
  • Major tyre damage will still leave a run flat trye unusable

So, Run Flats or Traditional?

There’s no right or wrong answer. Ultimately, it’s personal preference.

Many owners of vehicles fitted with run flat tyres, such as BMW, find the harsh ride of run flat tyres unbearable, and change back to traditional tyres at the very first opportunity – usually as soon as it’s time to replace the vehicle’s original set of tyres.

It’s worth remembering though that those vehicles fitted with run flat tyres from new are not equipped with a spare wheel and tyre in the boot. If you change from run flats to traditional tyres, a puncture could leave you completely stranded at the side of the road.

Or you call that tow truck and wait.

On the other hand, motorists who regularly drive long distances value the security and peace of mind of knowing that should they experience a puncture on a road trip, run flat tyres allow them to continue driving until they safely reach a tyre shop or arrive home.

BUT – run flat tyres are not as commonly available as traditional tyres, so you may limp to a tyre shop on your run flats, only to find they don’t have a replacement in stock.

If you want to discuss your individual tyre requirements please contact the team at John Dale Motors, Charmhaven. We will be happy to advise you on the best tyre solutions for your needs based on our many years of experience.

Space Saver Wheels and Tyres

Space Saver Wheels and Tyres

If your newer vehicle is equipped with traditional tyres, the chances are it has a space saver spare wheel and tyre rather than full-size.

Space savers are smaller and narrower than traditional spare wheels in an effort by car manufacturers to free up more boot space and save weight. Reducing the overall weight of a vehicle helps improve fuel economy and reduce exhaust emissions.

Because they are smaller, space saver tyres offer less tread depth and grip than regular tyres, so there are strict limits on how fast and how far you can travel on them.

Typically, a maximum safe speed of 80 km/h is common, but check your owners manual.

If you’re towing a trailer or caravan, using a space saver temporarily at low speeds may be allowed, but again,  check your owner’s manual and with your insurance company to see if there’s any vehicle or insurance specific advice on this.

Mixing New and Used Tyres – a Problem For Your AWD

Mixing New and Used Tyres

As we’ve highlighted in our tyre blogs, it never makes sense to cut corners when it comes to replacing your tyres.

Replacing just one or two tyres on an AWD vehicle could even cause unnecessary wear and tear to your drivetrain or confuse the traction control system into thinking that you are constantly losing traction.

What causes this?

Because of the kilometres already travelled by older tyres, a brand new tyre is larger in diameter (more tread) than an older tyre of the same type and size (less tread). This difference in tread depth means there’s a measurable difference in tyre circumference, and this can affect your vehicle’s performance.

Here’s how …

A tyre with more tread depth is taller, so it travels a longer distance in one single revolution than an older tyre with less tread depth. In order to keep up, the tyre with less tread depth will spin faster and have more revolutions than the tire with more tread depth.

Even a slight difference in tread depth between front and rear tyres on your AWD can mean trouble for the drivetrain. These are the components that transfer the power from the engine to the wheels and move the vehicle forward.

Most of today’s AWD systems include sensors at each wheel that monitor traction and wheel speed many times per second. This is what allows the AWD system to adapt to slippery conditions, by sending power to whatever wheels have the most traction.

If any of the tyres are spinning faster than any of the others, your car’s electronics will be fooled into thinking the tyre is slipping and unnecessarily transfer power to compensate for false driving conditions.

When smaller tyres are spinning faster, some systems may put your vehicle into four-wheel lock, the mode used for driving in slippery conditions. Driving in that mode on tarmac or at speed may cause damage to your vehicle’s drivetrain and result in expensive repairs.

Check out the ‘AWD Tyres’ video in the links below for an animated explanation of this issue.

Useful Video Links

Contact John Dale Motors

The team at John Dale Motors Charmhaven are proud of our reputation for technical excellence and outstanding customer service on the New South Wales Central Coast. We look forward to welcoming you.

John Dale Motors

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Delivering expert car servicing and repairs for most makes and models, combined with outstanding customer service to motorists in Charmhaven and throughout the Central Coast.


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