Side Wall Information


Every tyre can have different sets of codes moulded onto its sidewall. Each digit will have a purpose and meaning. The codes may denote the size of the tyre, its construction, manufacturing date, load capacity, ply rating, and other information which shows that the manufacturer certifies the tyre meets various industry standards and government regulations.


This signifies that the tyre meets or exceeds the US Department of Transportation’s safety standards.


Digits 1 and 2 indicate the manufacturer and plant. Digits 3 and 4 are a tyre size code. Digits 5, 6, 7 are for optional use.


Digits 8 and 9 designate the week (1-52) of the year, in this case, the 1st.


Digits 10 and 11 represent the last digits of the year of manufacturing, in this case, 2009.


The load index indicates the maximum weight that a tyre can hold vertically at the given PSI (pounds per square inch). Load indexes are determined using an applied vertical force against a tyre under laboratory conditions. The speed rating for the tyre can affect the maximum load the tyre can handle at a given temperature. The load index is often displayed as a combination of load and speed, such as 154/150M Usually there are two components to the load index – a rating for single tyre and wheel assemblies, and a rating for duals (two tyres bolted together). For this tyre, 154 is the single tyre load index and 150 is the dual tyre load index.


he speed symbol is a letter code that indicates the maximum speed a properly infl ated tyre will withstand for a determined amount of time on an indoor test drum. The speed symbol denotes the maximum speed capacity of the tyre under properly controlled conditions. They are not applicable if the tyres are under infl ated, overloaded, worn out, damaged or altered. Tyre speed ratings do not imply that the vehicle may be safely driven at the maximum speed for which the tyre is capable, particularly under adverse weather or road conditions. In this example, M stands for 130km/hr.

tyre size

This is the width of a new tyre when mounted on the tyre’s measuring rim, including normal sidewalls but not including protective side ribs, bars, raised letters, or decorations. On tubeless tyres with an aspect ratio of 80 or below (as shown here), section width will usually be displayed in millimetres, such as 315. On tube type tyres, the section width is generally displayed in inches, as in the ‘12’ in 12.00R24.


This describes the shape of the cross-section of the tyre. It is the section height divided by the section width multiplied by 100. Generally, truck and bus tube type tyres have 100 as the aspect ratio and are not separately mentioned; for example, 12.00R24.


The letter ‘R’ indicates radial construction. Bias ply construction is indicated by a dash (-).


This is the distance, in inches, from one bead base to the other (approximately the diameter of the hole that you see in the tyre). In this case, the rim diameter is 22.5 inches.


Serious injury may result from :

• Tyre failure due to under-inflation/overloading - follow owner's manual or tyre placard in vehicle.

• Explosion of tyre/rim assembly due to improper mounting - use safety cage and clip-on extension of air hose. Only specially trained persons should mount tyres.