What do the tyre markings mean on Pirelli tyres in australia

Tyre markings are essential for understanding the specifications and capabilities of your tyres. By decoding the letters and numbers on the tyre sidewall, you can make informed decisions about tyre safety, compatibility, and performance. This guide will provide an in-depth explanation of tyre markings, helping you to comprehend the critical information that tyres convey.

Components of a Tyre Code

1. Nominal Tyre Width

nominal tyre width marking

The nominal tyre width is a three-digit number following the vehicle type letter(s) on the tyre sidewall. This number, expressed in millimetres, indicates the tyre's width from sidewall to sidewall at its widest point. For example, a nominal width of 255 means the tyre is 255mm wide.

2. Aspect Ratio

pirelli tyre aspect ration

The aspect ratio represents the tyre's height as a percentage of its width. This figure is typically found after the nominal tyre width. An aspect ratio of 30 means that the tyre's height is 30% of its width, providing crucial information about the tyre's profile.

3. Internal Construction (R)

internal constructions tyre pirelli

The letter following the aspect ratio indicates the tyre's internal construction. The most common type is radial ply, denoted by the letter "R". Other types include bias ply (B) and diagonal (D). Radial ply construction is standard for most consumer tyres due to its superior performance and durability.

4. Rim Diameter Code

rim diametre code tyre marking on pirelli

The rim diameter code is a two-digit number that specifies the diameter of the rim the tyre is designed to fit. This measurement is in inches. For instance, a tyre with a rim diameter code of 19 is meant for 19-inch rims.

5. Load Index

speed and load rating markings on pirelli tyres

The load index is a numerical code that indicates the maximum load a tyre can carry at its maximum inflation pressure. This index does not directly state the weight in pounds or kilograms but corresponds to a standardized reference table. For example, a load index of 97 means the tyre can support a load of 730kg.

6. Speed Rating

The speed rating, indicated by a letter, denotes the maximum speed the tyre can sustain with a fully loaded vehicle according to its load index. For instance, the letter "V" means the tyre is rated for speeds up to 149 miles per hour.

Additional Tyre Information

DOT Code

The Department of Transportation (DOT) code is a 7 to 13 character code required by law. It starts with "DOT" and includes the tyre's manufacturing date, place of manufacture, size, and type. The last four digits indicate the week and year of manufacture, crucial for assessing tyre age and safety. For example, "1119" means the tyre was made in the 11th week of 2019.

Maximum Air Pressure

The maximum air pressure figure indicates the highest pressure to which the tyre should be inflated, expressed in PSI (pounds per square inch). This is not the recommended pressure, which should be followed as per your vehicle's manual or the driver's door sticker. Overinflating to the maximum can lead to premature wear and handling issues.

European ECE Type Approval

In the UK, tyres must have an approval mark to show conformity with European safety standards as per ECE Regulation 30. This mark comprises the letter "E" followed by a number indicating the approval country, such as "E11" for the UK.

Tread Wear Indicators

The legal minimum tread depth for car tyres in the UK is 1.6mm across the central three-quarters of the tyre's tread. Indicators, often marked as "TWI," help you check tread depth. Falling below this limit not only compromises safety but also risks hefty fines and points on your driving licence.

Other Tyre Markings

Additional markings may include:

  • Load Range: Indicates the tyre's toughness and maximum air pressure capacity, akin to the ply rating.
  • Material Composition: Information about the materials used in the tyre's construction.
  • M+S Marking: Signifies the tyre's capability in mud and snow conditions. True winter tyres also have a mountain peak with snowflakes symbol.