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Do you know your tyre load capacity?

This time of year, is very exciting as farmers wait in anticipation for the tobacco floors to open so they can start trading. The roads are busy with vehicles leaden with bales making their way to Harare. With this in mind Trentyre would like to share basic tyre knowledge that anyone can use to ensure tyre and vehicle safety for all road users.

Every sidewall of a tyre is filled with important information that can tell you everything you need to know about that tyre. The numbers at first can seem overwhelming to the untrained eye, so the best way to understand tyre markings is to take an example and break it down. Below is information to help you learn how to read a tyre size and other important tyre markings.

If a tyre size is 185/60 R14. Then the 185 represents its section width. The number "60" indicates the tyre’s aspect ratio and the last number, "14" indicates wheel diameter. To understand further:

Tyre Section Width, which in the above example is 185 tells us that the tyre is 185 millimetres wide, this is measured from sidewall edge to sidewall edge (over the tyre's tread). Generally speaking, the larger this number is, the wider the tyre will be.

Aspect Ratio refers to the ratio of the sidewall height to the section width. The sidewall height of the example tyre above is 60% of its section width. This number can be very indicative of a tyre's purpose. Lower numbers, like 55 or less, mean a short sidewall for improved steering response and better overall handling.

The (R) Internal Construction refers to radial construction, which has been the industry standard in passenger-car tyres for more than 20 years.

Rim or Wheel Diameter specifies the size, which is in inches, of the wheel that a tyre fits. The example tyre will only fit a 14-inch wheel. It is important to pay particular attention to this number if you plan on upgrading your wheel size. If your wheel diameter changes, you'll have to purchase a new set of tyres that matches this new diameter.

 

Sadly, what is often overlooked is the Load index, this is one of the most important numbers on your tyre. This can be found in the load rating of your tyre on the sidewall. The tyres load index relates to its maximum carrying capacity measured in kgs. for example, a tyre with a load index of 91 can carry 615kg of weight, times four tyres. The load index number is found just to the right of the diameter.

Overloading a tyre by carrying more weight than it is designed to carry, or running lower than specified pressure can cause heat build-up and destroy the tyre.

Load Ratings and Speed Ratings should be looked at together when you buy a new tyre. Also, remember to check your manufacturer’s recommendations, these can be found on the sticker in door jam.

It is also advisable to check your vehicle owner's manual to determine the load limits of your vehicle, which in turn will determine the tyres that are suitable for your vehicle. Overloading a vehicle places enormous stress on the tyres and other critical vehicle components, like the shocks and chassis. It can also cause poor handling, increased fuel consumption and may lead to tyre failure. It can also result in severe cracking, component separation or "blowout." 

Daniel Perlman, Managing Director of Trentyre; “When looking at replacing tyres for our vehicles we usually consider performance as the main factor during the selection process. It is also important to consider practicalities like what will you be using the vehicle for and what load the vehicle will be carrying and ensure that the tyres recommended by the vehicle manufacturer fulfil all the requirements. This is where an experienced Trentyre staff member can assist and give professional advice. With the tobacco season starting we want all road users to be aware of the carrying capacity of their tyres.”

The Load Index rating represents the load-carrying capacity of tyres inflated to the recommended maximum psi: This means the load-carrying capacity reduces as tyre pressures are reduced.

 

It is important to remember that a higher load rating equals a stronger tyre, so ithe tyre will run cooler under load, with the added benefit of a stronger tyre being more puncture resistant. It will also achieve higher mileage under normal operating situations.

When you are looking for new tyres to would be wise to consider: -

  1. Your vehicle’s minimum tyre load rating requirements
  2. What type of driving you are intending on doing? Especially any long-distance travels.
  3. Will the vehicle be carrying and or towing any heavy loads.

 

Daniel Perlman commented, “In most instances the best solution often turns out to be the easiest. A properly inflated tyre can benefit more than just the tread wear. It will help ensure that your vehicle is driving safely, extend the life of your tyre and of course not forgetting the benefit it will have on fuel-efficiency”.