It provides a cheap and effective method of identification that can be applied to the tyre during production or by field technicians at a later date.
Tyres Telford marking can also provide information such as load index and speed rating. This article aims to define how each component of the symbol contributes to its meaning; provide examples; and finally, describe how this information should be recorded on a label (which is usually attached to one side of the tyre).
The symbol consists of four main components: 1) A letter that defines what category or category range that tyre belongs to 2) A letter that defines the standard or optional tread design 3) A single-digit number that defines the ply rating 4) A letter which defines the tyre shape
Each component of a tyre mark has a meaning; when combined, they define that particular tyre's properties.
The classification letter defines the category or range that the tyre belongs to. For example: "Q" denotes a 'Passenger Car Tyre', "LT" denotes a 'Light Truck/SUV Tyre'. It is important to note that for some organisations (which we will discuss later), it may be necessary to add digits in brackets after this symbol.
- This additional digit represents the diameter in inches of the in-service rim for which this tyre has been designed: 123(14") and 123(15").
The standard Tyres tread design letter is only required in certain cases, such as recording a tyre's speed rating on its label. The ply rating digit defines the number of plies or layers in that tyre. A "5" means 5 plies in the tyre, whereas a "6" means 6, etc.
Please note that this does not define how many 'wraps' of fabric are used; it instead defines how many layers of rubber-coated fabric are contained within the tyre (i.e.: an 11-ply Tyres could mean 10 wraps of 2 plies each or 20 wraps of 1 ply each).
For example, 4(1) would indicate that the road/traction layer comprises four plies; however, 5(2) would indicate only three plies. The tyre shape letter defines the type of tread pattern and its cross-sectional shape.
In other words, this letter describes the three-dimensional appearance of the tyre's tread profile when looking from above or below it. For example, A denotes an 'Avon' tyre; C denotes a 'Computer Tyre'; D denotes a 'Directional tyre', etc.
The following table provides examples, in alphabetical order, of what each classification letter means:
A = Asymmetric B = Belted C = Computer Tyre D = Directional E = European Standard F = Dynamic G = Grand Touring I = Modified Non-Skid J = North American Standard L = Special Purpose N/A = Not Applicable P = Spare Q = Passenger Car R = Racing S = Standard T = Temporary Use U/W or V/W or Z/W or Y/V = European Non-Skid X, Y & Z = North American Non-Skid
The following table provides examples of tread design standard letters: A = Asymmetric B = Button C = Cast D E F G H I J K L M N P Q R S T U V W X Y Z
The following table provides examples of ply rating digits: 1 2 3 4 5 6 7 8 9 0 (zero)
For example, a tyre marked as "LT 225 70 R 15 98M" would be a 'Light Truck/SUV tyre (225mm Diameter) with the following properties: The ply rating is 8; it has an asymmetric tread pattern; it is designed for speeds less than 180 km/h; and, its in-service rim diameter is 15" (which applies to cars manufactured in North America).
We can now determine how this particular Tyres should be recorded on its label from the information above. Labels can be found on either side of a tyre's sidewall. They usually contain at least one line that reads "INFORMATION", where all of the relevant information about the tyre must be written. The symbols themselves are not always included on these labels due to space constraints, so instead, they are printed beside each entry to explain each one.
For example, the following label reads "INFORMATION LT225 70R15". We can see that this tyre has a ply rating of 8; it has an asymmetric tread pattern; it is designed for speeds less than 180 km/h, and its in-service rim diameter is 15".
Care must be taken when recording speed ratings on this side of the tyre's label because regionally specific requirements must be met. North American Tyres Telford are required to include both the letter designation (Q, P, etc.) and a number denoting its speed rating within parentheses after this symbol: Q (87).
- European tyres, however, require the letter designation: P (82). If a tyre's speed rating falls between two-letter designations, a number can denote the lower of the two ratings. For example: if a Tyres Arleston is designed for speeds up to 92 mph (148 km/h), its label would read Q (87)A-C.
The following table provides examples of other symbols found on tyre labels: LT = Light Truck/SUV PN/r = Passenger car speed rating only RT = Run Flat
LT = Light Truck/SUV
PNR or PRC or PMR or ZR or C - Passenger car speed rating only
RT - Run Flat
M+S - Mud and Snow
T - Temporary use of spare
DOT - Department of Transportation
Speed Rating Symbol: Q (87) P (82) A-C