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Sidewall Markings Explained

August 22, 2018
Sidewall Markings Explained

When looking for you’re next set of tyres, the first step is to correctly identify the size of your current set.

The manufacturer recommended size of your tyres can be found in the following places:

  • In the owner’s manual, typically in the ‘Specifications’ section

  • On a sticker in the glove box

  • On a sticker on the inside of your driver’s side door jamb

  • On each of your tyre sidewalls

Regardless of where you find your tyre sizing, the markings for passenger vehicle tyres will generally be the same. This guide explains how to interpret your tyre sidewall markings and how to use them when buying your next set of tyres.

If you’re still unable to find your tyre size, contact your local Bob Jane T-Marts or use our Tyre Finder to search which tyres will exactly fit your vehicle.

For commercial and 4x4 tyres, read our separate guide for more information!



Sidewall Markings

Brand & Pattern

sidewall_diagram_brand_pattern-bob-jane-t-marts-png

All tyres feature the brand and pattern description on the sidewall. In this instance, the brand is Bob Jane and the pattern is Xenon Z7.


Tyre Size

sidewall_diagram_aspect_r-png

Width: The tyre measured in millimetres from the two widest points, in this case, it's 235mm.

Profile: The aspect ratio of the tyre, which is the height of the sidewall as a percentage of the width, which in the example it’s 40%.

Wheel size: Diameter of the wheel rim that the tyre is designed to fit, measured in inches, which is 18” in the example above.


Directional Marking

sidewall_diagram_rotation-bob-jane-t-marts-png

Directional tyres have been designed specifically to operate best when rotating in one direction.

The tyre pattern is usually in the shape of an arrow, with grooves running from the centre rib (middle) of the tyre to the outer shoulders. First engineered for racing in wet conditions, directional road tyres have excellent wet weather performance, due to their ability to displace large amounts of water from the road surface, while providing directional stability.

If you have a pair of directional tyres on your vehicle, they will usually have either an arrow or similar symbol indicating the direction they are designed to operate.


Speed Rating, Tyre Load & Pressure

speed-rating-and-load-pressure-diagram-png

Tyre Pressure: Nearly all manufacturers print a maximum inflation pressure on the sidewall of the tyre. It is important to note that this is generally not the recommended operating pressure for that tyre. If you are unsure of the correct inflation pressure for your tyres or the pressure description is missing, simply [enquire at your local T-Mart] or reference the tyre placard on your vehicle.

Load Index: A numerical code associated with the maximum load a tyre can carry when inflated to operating pressure. In the above example, it’s 88, which equals 560kg in load per tyre.

Speed Category Symbol: This indicates the maximum safe operating speed for the tyre when carrying a load within its load index rating. In the example, it’s V, which indicates a maximum rated speed of 240km/h.

For more information view the load and speed rating guide for full details.



Now that you’ve identified the size of your tyres, the next step is to input the sizing into the Tyre Search to find all the tyres that match that size.

If you’re unable to find your tyre size or need help choosing the best tyres for your vehicle, contact your local Bob Jane T-Marts or use our Tyre Finder tool.

Some vehicles will have different sized front and rear tyres, so it’s important to check both and not assume both will be the same.

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