matespace
11-05-2015, 04:26 PM
A tyre is black and round, right? Wrong!
Tyres have different tread patterns, compounds, widths, sidewall sizes, and speed ratings. This information is written on the sidewall of the tyre as a series of numbers and letters, which can be confusing and even intimidating - unless you know what they mean.
Don't despair; the numbers are actually easy to understand once you know how.
Let's say the large set of numbers on the sidewall of a tyre reads 215/45 R17 84V.
http://i762.photobucket.com/albums/xx270/go2spacebucket/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%201.jpg (http://s762.photobucket.com/user/go2spacebucket/media/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%201.jpg.html)
215 - This is the width of the tyre across its tread in millimetres. If you took a ruler and measured the tread, it would read about 21.5cm, or 215mm.
http://i762.photobucket.com/albums/xx270/go2spacebucket/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%202.jpg (http://s762.photobucket.com/user/go2spacebucket/media/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%202.jpg.html)
45 - This is the width of the sidewall, as a percentage of the width of the tread. This tyre's sidewall is 45 percent of the tread. If you measured it with a ruler, it would be just under 10cm. An off-road tyre or a tyre designed for comfort will usually have a higher profile number. A performance tyre, also known as a 'low profile' tyre, will have a smaller profile.
http://i762.photobucket.com/albums/xx270/go2spacebucket/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%203.jpg (http://s762.photobucket.com/user/go2spacebucket/media/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%203.jpg.html)
R17 - The R stands for radial; this is a radial road tyre. The 17 is the diameter of the wheel or rim in inches, therefore this tyre is designed for a 17-inch rim. Want to check what size your rim is? The size is typically stamped inside the rim on one of the spokes, or you can measure across the spokes from one inside edge to the other.
91W - this is the load index and speed rating of the tyre. Essentially, the load rating, represented by the numerical value, is related to the maximum weight that tyre can carry. The tyres load index must meet or exceed the value displayed on the vehicle's tyre placard (see below). The speed category symbol, represented by the alphabetical value, indicates the maximum speed at which the tyre can carry a load corresponding to its load index.
Finding the right load and speed rating for your vehicle is a bit trickier, as you need to cross-reference these values with a chart to find the right tyre. The best thing to do is ask the experts to check your tyre is correct for your vehicle and what you plan to do with it.
The Tyre Placard
It's important to have the right tyres fitted to your vehicle for safety reasons as well as from both a legal and insurance perspective.
http://i762.photobucket.com/albums/xx270/go2spacebucket/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%204.jpg (http://s762.photobucket.com/user/go2spacebucket/media/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%204.jpg.html)
This is the tyre placard from a Subaru Impreza.
It shows 3 different the 3 different tyre sizes available across the range. The 2009 Subaru Impreza WRX which has this placard is fitted with tyre option B with a 225/45R17 tyre size and a 91 load rating with a W speed rating.
The placard says that if the car is loaded with 3 people and a small amount of baggage or cargo the front tyres should be inflated to 230 kPa (That's about 33 psi). The rear tyres should be inflaed to 220 kPa (That's about 32 psi).
If the Subaru Impreza was loaded with 5 adults and full of luggage it would need more tyre pressure to carry the additional weight. So the recommended tyre pressure for the rear would increase from 220 kPa to 230 kPa.
If the Subaru was towing a trailer the rear tyre pressure would be increased to 250 kPa (That's about 36 psi).
http://i762.photobucket.com/albums/xx270/go2spacebucket/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding20Tyre20Markings20and20Setting20Press ures20-205.jpg (http://s762.photobucket.com/user/go2spacebucket/media/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding20Tyre20Markings20and20Setting20Press ures20-205.jpg.html)
The Subaru Impreza has its tyre placard in the driver's door jam.
http://i762.photobucket.com/albums/xx270/go2spacebucket/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding20Tyre20Markings20and20Setting20Press ures20-206.jpg (http://s762.photobucket.com/user/go2spacebucket/media/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding20Tyre20Markings20and20Setting20Press ures20-206.jpg.html)
A Holden Barina has its tyre placard on the glovebox door.
Since January 1973, new vehicles have been required by law to have a tyre placard affixed to the car, usually on the driver's door pillar or inside the fuel filler cap.
This placard will tell you the factory fitted tyre sizes and recommended tyre inflation pressures for the vehicle. You should locate the placard on your vehicle and become familiar with this important information.
For more information on Tyre Specifications click HERE (http://clixtrac.com/goto/?199366)
Or visit the Yokohama website: http://www.yokohama.com.au/Footer/Useful-Links/Tyre-Sizes-and-Pressures.aspx
Tyres have different tread patterns, compounds, widths, sidewall sizes, and speed ratings. This information is written on the sidewall of the tyre as a series of numbers and letters, which can be confusing and even intimidating - unless you know what they mean.
Don't despair; the numbers are actually easy to understand once you know how.
Let's say the large set of numbers on the sidewall of a tyre reads 215/45 R17 84V.
http://i762.photobucket.com/albums/xx270/go2spacebucket/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%201.jpg (http://s762.photobucket.com/user/go2spacebucket/media/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%201.jpg.html)
215 - This is the width of the tyre across its tread in millimetres. If you took a ruler and measured the tread, it would read about 21.5cm, or 215mm.
http://i762.photobucket.com/albums/xx270/go2spacebucket/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%202.jpg (http://s762.photobucket.com/user/go2spacebucket/media/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%202.jpg.html)
45 - This is the width of the sidewall, as a percentage of the width of the tread. This tyre's sidewall is 45 percent of the tread. If you measured it with a ruler, it would be just under 10cm. An off-road tyre or a tyre designed for comfort will usually have a higher profile number. A performance tyre, also known as a 'low profile' tyre, will have a smaller profile.
http://i762.photobucket.com/albums/xx270/go2spacebucket/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%203.jpg (http://s762.photobucket.com/user/go2spacebucket/media/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%203.jpg.html)
R17 - The R stands for radial; this is a radial road tyre. The 17 is the diameter of the wheel or rim in inches, therefore this tyre is designed for a 17-inch rim. Want to check what size your rim is? The size is typically stamped inside the rim on one of the spokes, or you can measure across the spokes from one inside edge to the other.
91W - this is the load index and speed rating of the tyre. Essentially, the load rating, represented by the numerical value, is related to the maximum weight that tyre can carry. The tyres load index must meet or exceed the value displayed on the vehicle's tyre placard (see below). The speed category symbol, represented by the alphabetical value, indicates the maximum speed at which the tyre can carry a load corresponding to its load index.
Finding the right load and speed rating for your vehicle is a bit trickier, as you need to cross-reference these values with a chart to find the right tyre. The best thing to do is ask the experts to check your tyre is correct for your vehicle and what you plan to do with it.
The Tyre Placard
It's important to have the right tyres fitted to your vehicle for safety reasons as well as from both a legal and insurance perspective.
http://i762.photobucket.com/albums/xx270/go2spacebucket/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%204.jpg (http://s762.photobucket.com/user/go2spacebucket/media/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures%20-%204.jpg.html)
This is the tyre placard from a Subaru Impreza.
It shows 3 different the 3 different tyre sizes available across the range. The 2009 Subaru Impreza WRX which has this placard is fitted with tyre option B with a 225/45R17 tyre size and a 91 load rating with a W speed rating.
The placard says that if the car is loaded with 3 people and a small amount of baggage or cargo the front tyres should be inflated to 230 kPa (That's about 33 psi). The rear tyres should be inflaed to 220 kPa (That's about 32 psi).
If the Subaru Impreza was loaded with 5 adults and full of luggage it would need more tyre pressure to carry the additional weight. So the recommended tyre pressure for the rear would increase from 220 kPa to 230 kPa.
If the Subaru was towing a trailer the rear tyre pressure would be increased to 250 kPa (That's about 36 psi).
http://i762.photobucket.com/albums/xx270/go2spacebucket/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding20Tyre20Markings20and20Setting20Press ures20-205.jpg (http://s762.photobucket.com/user/go2spacebucket/media/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding20Tyre20Markings20and20Setting20Press ures20-205.jpg.html)
The Subaru Impreza has its tyre placard in the driver's door jam.
http://i762.photobucket.com/albums/xx270/go2spacebucket/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding20Tyre20Markings20and20Setting20Press ures20-206.jpg (http://s762.photobucket.com/user/go2spacebucket/media/YOKOHAMA/Understanding%20Tyre%20Markings%20and%20Setting%20 Pressures/Understanding20Tyre20Markings20and20Setting20Press ures20-206.jpg.html)
A Holden Barina has its tyre placard on the glovebox door.
Since January 1973, new vehicles have been required by law to have a tyre placard affixed to the car, usually on the driver's door pillar or inside the fuel filler cap.
This placard will tell you the factory fitted tyre sizes and recommended tyre inflation pressures for the vehicle. You should locate the placard on your vehicle and become familiar with this important information.
For more information on Tyre Specifications click HERE (http://clixtrac.com/goto/?199366)
Or visit the Yokohama website: http://www.yokohama.com.au/Footer/Useful-Links/Tyre-Sizes-and-Pressures.aspx