RATIO
The relationship between a tyre’s sidewall height and its width.
DOT MARKINGS
A code (tyre identification number) moulded on the sidewall to show that the tyre meets the safety standards of the U.S. Department of Transportation (DOT). The DOT code is followed by ten, eleven, or twelve letters and/or numbers that identify the place of manufacture, tyre size, manufacturer code, and the week and year of production.
LOAD CAPACITY
Indicates the maximum load a tyre can carry at a given maximum pressure.
LOAD INDEX
A value between 0 and 279 representing the maximum load a tyre can carry.
OVERALL DIAMETER
The diameter of the inflated tyre without load.
OVERALL WIDTH
The distance between the outer edges of both sidewalls, including markings and patterns.
TYRE SIZE
The combination of tyre width, construction type, aspect ratio, and rim diameter used to differentiate tyres.
SPEED RATING
The speed rating indicates the maximum safe speed at which a tyre can operate under specified conditions. Nominal ratings range from A (lowest) to Y (highest).
TYRE DESIGNATION
An alphanumeric code moulded into the tyre sidewall that describes its size, including width, aspect ratio, rim diameter, and load and speed indices. Most designations use the P-metric system.
TYRE BRAND
The brand or manufacturer of your tyre.
TYRE TREAD NAME
The tread name is the model or designated name of a specific tyre. This is usually listed on the sidewall after the manufacturer’s name.
TYRE WEAR INDICATOR
Tread wear indicators (“wear bars”) are located at the base of the main grooves and spaced around the tyre. These narrow bands of smooth rubber appear when the tyre reaches its wear limit. When visible, it indicates the tyre should be replaced. Replace your tyres when the remaining tread depth reaches 2 mm. You can also use a coin test: insert a 10-cent euro coin into the tread groove with the face side down. If the tread covers the top of the coin, the tyres are in good condition. If it does not, it’s time to replace them.
TYRE TYPE
Indicates the type of vehicle the tyre is intended for. P is used for passenger vehicles. Other letters include LT (light truck), T (temporary/spare), and ST (special trailer). If no letter is present, it is a European “metric” size tyre.
TYRE WIDTH
The width of the tyre from one sidewall to the other. In this example, the tyre width is 225 mm.
ASPECT RATIO
The ratio of the tyre’s sidewall height to its width. In this example, the sidewall height is 55% of the tyre’s width. Lower ratios mean shorter sidewalls, improving cornering grip but reducing comfort.
TYRE CONSTRUCTION
The internal structure of the tyre, typically “radial.” Most road tyres are radial, meaning the cords in the carcass plies run directly across the tyre from side to side. Other letters include D for diagonal construction and B for belted construction.
RIM DIAMETER
This number (in inches) indicates that the tyre is designed to fit an 18-inch diameter wheel.
The relationship between a tyre’s sidewall height and its width.
DOT MARKINGS
A code (tyre identification number) moulded on the sidewall to show that the tyre meets the safety standards of the U.S. Department of Transportation (DOT). The DOT code is followed by ten, eleven, or twelve letters and/or numbers that identify the place of manufacture, tyre size, manufacturer code, and the week and year of production.
LOAD CAPACITY
Indicates the maximum load a tyre can carry at a given maximum pressure.
LOAD INDEX
A value between 0 and 279 representing the maximum load a tyre can carry.
OVERALL DIAMETER
The diameter of the inflated tyre without load.
OVERALL WIDTH
The distance between the outer edges of both sidewalls, including markings and patterns.
TYRE SIZE
The combination of tyre width, construction type, aspect ratio, and rim diameter used to differentiate tyres.
SPEED RATING
The speed rating indicates the maximum safe speed at which a tyre can operate under specified conditions. Nominal ratings range from A (lowest) to Y (highest).
TYRE DESIGNATION
An alphanumeric code moulded into the tyre sidewall that describes its size, including width, aspect ratio, rim diameter, and load and speed indices. Most designations use the P-metric system.
TYRE BRAND
The brand or manufacturer of your tyre.
TYRE TREAD NAME
The tread name is the model or designated name of a specific tyre. This is usually listed on the sidewall after the manufacturer’s name.
TYRE WEAR INDICATOR
Tread wear indicators (“wear bars”) are located at the base of the main grooves and spaced around the tyre. These narrow bands of smooth rubber appear when the tyre reaches its wear limit. When visible, it indicates the tyre should be replaced. Replace your tyres when the remaining tread depth reaches 2 mm. You can also use a coin test: insert a 10-cent euro coin into the tread groove with the face side down. If the tread covers the top of the coin, the tyres are in good condition. If it does not, it’s time to replace them.
TYRE TYPE
Indicates the type of vehicle the tyre is intended for. P is used for passenger vehicles. Other letters include LT (light truck), T (temporary/spare), and ST (special trailer). If no letter is present, it is a European “metric” size tyre.
TYRE WIDTH
The width of the tyre from one sidewall to the other. In this example, the tyre width is 225 mm.
ASPECT RATIO
The ratio of the tyre’s sidewall height to its width. In this example, the sidewall height is 55% of the tyre’s width. Lower ratios mean shorter sidewalls, improving cornering grip but reducing comfort.
TYRE CONSTRUCTION
The internal structure of the tyre, typically “radial.” Most road tyres are radial, meaning the cords in the carcass plies run directly across the tyre from side to side. Other letters include D for diagonal construction and B for belted construction.
RIM DIAMETER
This number (in inches) indicates that the tyre is designed to fit an 18-inch diameter wheel.