Tag Archives for " New tyres in Brisbane "


Read this warning before you go large on new tyres

New tyre tips to stay legal when you modify your vehicle

In my last article, “Should you check your speedo when you fit new tyres?”, I explained how fitting the wrong-sized new tyres on your vehicle could lead you to break the speed limit even though your speedometer tells you otherwise. This isn’t the only problem you may have if you want to supersize your tyres.

Why you might want larger tyres

If you want extra power, there are many things you can do to your vehicle. You might decide to refit the engine and have it tuned especially for the job your vehicle needs to do. You might fit a supercharger, upgrade the suspension, or replace the turbo.

None of these upgrades will help your vehicles grip on the road. All the power in the world will add up to nothing if you can’t get traction. So, naturally, you’ll look to new tyres. Bigger is better, right? Especially when it comes to grip on the road. A tyre with a wider diameter will give you that grip. It could also void your insurance.

Stay legal with larger tyres

Whatever new tyres you have fitted, they must comply with the law. If you are modifying your vehicle in any way, you must do so in line with the National Code of Practice for Light Vehicle Construction and Modification (NCOP) Vehicle Standards. Regarding new tyres, this code is clear that:

  • New tyres fitted to 4WD passenger vehicles must not be more than 50mm wider in diameter than the tyre size designated by the vehicle’s manufacturer
  • New tyres fitted to off-road passenger vehicles must not be more than 50% wider than the vehicle manufacturer’s recommended widest tyre

You’ll find the manufacturer’s recommendations on the tyre placard on the door jamb, or in the owner’s manual.

Whatever modification you make, you must also ensure that no part of the wheel or tyre touches:

  • Any part of the body of the vehicle
  • The chassis
  • The steering mechanisms
  • The braking system
  • The suspension

Also, when aligned straight, the wheels must be housed within the bodywork – they cannot stick out from the side of your vehicle.

Modify your vehicle legally

If you are modifying your vehicle, and there are many reasons why you might wish to do so, the chances are that you’ll need to consider what to do with your wheels and which new tyres to fit.

A larger-diameter tyre will improve clearance if you do a lot of off-road driving. Increasing the diameter of your tyre will give you the added traction you need to benefit from increased power and retain safe braking distances.

However, by modifying your wheels incorrectly you run the risk of the modification being illegal. If you get into an accident and this is the case, your insurance will be void. You could find yourself with a huge cost to pay.

Modifying your vehicle and fitting new tyres without the technical know-how and legal knowledge is not a smart thing to do. Instead, bring your vehicle into our tyre shop in Darra. We’ll help you decide on the best modification and the best tyres to get the most from your vehicle while staying legal and ensuring your insurance covers what you believe it does.

For a professional and personal tyre service that you can trust, contact Darra Tyres today.

Keeping your family and fleet safe,

Kevin Wood


Should you check your speedo when you fit new tyres?

The wrong-sized tyres could land you with a speeding fine

The Head of Engineering at the Royal Automobile Club of Queensland (RACQ) has recently warned motorists that if they have new tyres fitted, they may need to consider having the speedometer checked. If you have new tyres fitted, you could drive faster than the speed limit without realising it. I know this sounds strange, but let me explain.

Why you may drive faster on larger tyres

If you have new tyres fitted that are larger than recommended by the car manufacturer, it could mean that your speedometer doesn’t show the real speed at which you are driving. You may think you’re travelling at 60 kph, but you could be moving at nearer 70 kph or faster.

This is because larger tyres move relatively faster than smaller tyres. One revolution of the axle will turn your tyres one revolution. A larger tyre may be, say, 115 cm in circumference, compared to a smaller tyre with a circumference of, say, 100 cm. Though your axle is rotating at the same speed, the larger tyre will move you a greater distance – an extra 15 cm per revolution.

When it is manufactured, a vehicle’s speedometer is calibrated to record the speed based upon the manufacturer’s recommended tyre size. In our example, it records one revolution of the axle as 100 cm. If you are driving with larger tyres, your vehicle records the same speed even though you are moving a greater distance.

So, in our example, you may think you are travelling at 60 kph, but because your tyres are 15% larger, you will be travelling at 69 kph.

How to avoid breaking the speed limit because of new tyres

Australian law says that the speedometer should be calibrated on the safe side. This should be around 10% to 15% faster than your actual speed. In other words, the speed that your speedometer tells you that you are travelling at will be faster than your actual speed. You believe you are travelling at, say, 110 kph and your actual speed is likely to be 100 kph.

So, how do you make sure that your speed is not faster than it should be?

When you have new tyres fitted, the technician should refer to the tyre placard found on your door jamb. This tells us what size tyres match the vehicle. Providing the tyres fitted are the right size as per the manufacturer’s recommendations, then you should not get a misreading on your speedometer. With the right tyre size fitted, if your speedometer tells you are driving within the speed limit, then you should be fine.

Don’t rely on your Sat Nav to tell you the correct speed

I love the Sat Nav, but I would never rely on it to tell me how fast I’m travelling. It may give a good indication, but it is not calibrated to your vehicle or its tyres.

How do you know you need your speedo recalibrated?

Providing you always fit the correct size tyres, your speedometer should retain its accuracy. But, like all mechanical equipment, they do go wrong sometimes. There are two tell-tale signs that you may either be driving on the wrong-sized tyres or that you need your speedo checked for accuracy:

  • Your speedometer and Sat Nav show wildly different speeds of 20% or more discrepancy
  • Other vehicles are travelling either faster or slower, despite your speedo showing you are driving at the speed limit

If you notice either of these two things happening, take your vehicle to your nearest tyre fitter immediately. They will be able to check that your tyres are the correct size for your vehicle, and advise on whether speedometer calibration is needed.

Finally, always make sure that you use a reputable tyre service and that the technician changing your tyres checks the tyre details on the tyre placard.

For a tyre service, you can trust in Brisbane, contact Darra Tyres today.

Keeping your family and fleet safe,

Kevin Wood