All About Tyres

     

Reading your Tyre Size

Tyre Diagram

Q. What does reading my tyre mean?

The information on the sidewalls of your existing tyres is the first important step in selecting new tyres for your car. It looks something like 205/65 R16 95 V. Having this information will make the selection of your next set of tyres a lot quicker and easier.

 

Q. What is the width?                  205/65 R16 95 V

The width of the tyre.

 

Q. What is the aspect ratio?         205/65 R16 95 V

The Aspect ratio or profile is the height of the tyre form the rim to the tread area. It’s shown as a percentage of the tread width. In this case the “height” of the tyre is 65% of the width.

 

Q. What does the R stand for?     205/65 R16 95 V

R is for Radial and tells us the “construction type” of the tyre. It is less important these days as all car tyres are radial. Many years ago we had  “bias ply” or “cross ply” constructions as well and they needed to be able to identify the different types of tyre since they could not be mixed on the same axle. If there is no 'R', the tyre is not a radial.

 Tyre Dimensions

Q. What is the rim diameter?       205/65 R16 95 V

This is the diameter of the rim that the tyre can be fitted to. Internationally rim sizes are still measured and quoted in inches. See 'With Rims, Inches Rule' in our blog.

 

Q. What is the load rating?          205/65 R16 95 V

A type of shorthand or scale used to describe the load carrying capacity of each tyre is. See load rating table. The higher the number, the more load the tyre can carry at a higher pressure. See load rating categories.

 

Q. What is the speed Rating?       205/65 R16 95 V

The speed symbol indicates the maximum speed the tyre is capable of running. In the case of a V rated tyre its 240kph. While it may seem excessive having such high speed ratings on tyres in Australia these ratings come almost as a “by product” of more highly developed tyres. A higher speed rating generally improves the tyre's ability to withstand heat (eg. driving long distances in hot conditions). See the speed categories and 'Tyre Pressures' in our blog.

 

Q. Where do I find the name of the Tyre Brand?

It’s good to know what the existing brand is on the vehicle, it’s a big help as you start the selection process, usually the biggest lettering on the tyre.

Q. What is the Tread Pattern Description (Tyre Model)?

Equally as important is the tread pattern description, especially the detail of tread pattern numbers. Some tyres have a common “sub brand” for example Bridgestone Potenza or Turanza and Goodyear Wrangler .The actual tread pattern reference is a series of numbers that follow this brand, such as ER30 or RE050 in the case of the Bridgestone’s. These are actually the tread pattern descriptions.

Q. What other information is on the tyre sidewall?

Some tyres have a detailed amount of information in a small box close to the area where the tyre joins the rim. Here you will find:

  • Maximum Inflation Pressure – the maximum pressure the manufacturer recommends for the tyre. These pressures are usually well in excess of the operating pressures required for most conditions. The vehicle manufacturer will have recommended pressures for the vehicle which can be found in the handbook or on the tyre placard which can be usually found around the drivers door frame, end of the door or on the glovebox lid. Operating pressures allow for a driver and 2 passengers (normal load) and driver, all seats full, plus luggage (high load). Then pressure increases for sustained high speed. 
  • Tyre Component Description -  this will give details as to how many steel belts are in the tread, what materials were used in sidewalls and casing and how many “plies” were used. These days this reference to plies is to how many layers of material are used. It does not give any real indication to the load carrying capacity of the tyre. See 'Why Pay More' in the Choose the Right Tyre section of the All About Tyres .

See 'Reading a Tyre’s Message' , and 'Tyre Pressures' in the CarbonBlack blog.

     
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