How to Read Tyre Size and Manufacture Date?
Tyres contain a wealth of important details, including size, load index, speed rating, and manufacturing date.
1) By size
The first step in reading a tyre is understanding its size. It is typically represented by a series of numbers and letters, such as P205/55R17.
- The "P" indicates that it is a passenger tyre, followed by the tyre's width in millimetres (225).
- The aspect ratio (45), which represents the height of the tyre's sidewall as a percentage of its width.
- The "R" denotes that it is a radial tyre.
- The final number (17) represents the diameter of the wheel in inches.
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2) Load index and speed rating
- The load index indicates the maximum weight the tyre can safely carry, and it is represented by a numerical value.
- The speed rating indicates the maximum speed at which the tyre can maintain its performance, and it is represented by a letter.
Both the load index and speed rating can be found on the sidewall of the tyre, following the tyre size.
3) Tread wear indicators
Inspecting the tread of your tyres is crucial for monitoring their condition. Tyres have tread wear indicators, small bars located at various points within the grooves of the tyre. When the tread wears down to the level of these indicators, it is a sign that the tyre has reached the minimum allowable depth, indicating the need for replacement.
4) Manufacturing date
To determine the age of a tyre, you can locate the DOT (Department of Transportation) number on the sidewall. The last four digits of this number indicate the week and year of manufacture.
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For example : "2712" means the tyre was manufactured in the 27th week of 2012.
It is important to be aware of the age of your tyres, as they can deteriorate over time, even with minimal use.
5) Additional information
Tyres may also display other information, such as the tyre brand, specific model, and any additional features or technologies employed in their construction. Familiarise yourself with these details to understand the characteristics and benefits of your specific tyre model.
Recommended tire pressure (PSI) varies; check your vehicle's manual or the driver's side door jamb for the correct PSI. Normally it is between 1.8 and 2.2 bar or 30 to 35 PSI. (1 bar = 14,5 PSI).
Can I put 55 tires instead of 50?
In most cases, it's acceptable to use a higher load index tire (e.g., 55 instead of 50) as long as it meets or exceeds the manufacturer's specifications.