What The Numbers & Letters On Your Tires Mean

For the average car guy, the numbers and letters on the sidewalls of a tire don’t mean anything at all. For as long as the tires are well inflated most of the time, those marks are overlooked. It might not be as important as keeping our tires’ recommended psi (tire pressure) but those numbers have meanings and understanding what the label means actually helps us how to properly care for our tires.



Let’s try to identify the label as shown from the image above. The first three-digit number, 225 is the tire width in millimeters measured at its widest from sidewall to sidewall, not the tread width. Tire width varies depending on the rim. Understandably, Wide rim comes with wide tires and vice versa. 50, the two-digit number after the slash symbol means the sidewall height measured from the rim edge up to the surface of the tread. It’s not a direct measurement but rather the aspect ratio of the tire. It means that the height of the tire is 50% of its width which is 225 millimeters or 225x.50 = 112.5 Millimetres.


After the aspect ratio is letter R which stands for Radial Tire Construction. It tells how the internal reinforcing cables of the tires were made. R is usually for cars and D (diagonal) is commonly used for trucks. Next to it is 17 which is the size of the rim in inches.


Load Index & Speed Rating


Next is the load index or the maximum load your tire can support. Based on the load index chart, the service description of 98 is able to support up to 749 kg. The letter next to the load index is the Speed Rating. H speed rating means a tire is able to go up to 130 mph (210 km/h)


Let’s try to identify the label as shown from the image above. The first three-digit number, 225 is the tire width in millimeters measured at its widest from sidewall to sidewall, not the tread width. Tire width varies depending on the rim. Understandably, Wide rim comes with wide tires and vice versa. 50, the two-digit number after the slash symbol means the sidewall height measured from the rim edge up to the surface of the tread. It’s not a direct measurement but rather the aspect ratio of the tire. It means that the height of the tire is 50% of its width which is 225 millimeters or 225x.50 = 112.5 Millimetres.


After the aspect ratio is letter R which stands for Radial Tire Construction. It tells how the internal reinforcing cables of the tires were made. R is usually for cars and D (diagonal) is commonly used for trucks. Next to it is 17 which is the size of the rim in inches.


Load Index & Speed Rating


Next is the load index or the maximum load your tire can support. Based on the load index chart, the service description of 98 is able to support up to 749 kg. The letter next to the load index is the Speed Rating. H speed rating means a tire is able to go up to 130 mph (210 km/h).



Tire’s Birthdate

The four-digit number on your tire, as shown above, indicates the date when a tire was manufactured. The first two digits - 26 is the 26th week of the year and 16 stands for the year 2016. Knowing this is very important as even if your tire may still have thick treads if it’s more than 10 years old it will affect the performance and overall safety and capability of your vehicle.

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