On the sidewall of all tyres you can find the Load Index and Speed Symbol for that tyre (following the key sidewall markings) for example 105 S.
The load rating (represented by the numerical value) is related to the maximum weight that tyre can carry. So in this case 105 would refer to a load capacity of 925kg, with most passenger vehicle load indexes range from 62 to 126.
In all instances the tyres load index must meet or exceed the value displayed on the vehicles placard.More Details
|Load index||Load in Kg per tyre|
The speed category symbol, for example 'S', indicates the maximum speed at which the tyre can carry a load corresponding to its load index. So in this case, 'S' would refer to a maximum speed of 180km/hour See the chart below for a full list of speed symbols and their applicable values.More Details
|Speed Symbol||Speed in kmh|
*A tyre with ZR symbols have a speed capability of over 240km/h. Your T-Mart can always consult with the tyre manufacturers to ascertain the tyres actual speed capabilities. The legal speed symbol requirements vary by state, please check with your local T-Mart.
Ply ratings identify the load carrying capacities of a tyre in terms of plies. Ply rating originally referred to the number of cotton layers used to strengthen a tyre's casing. Today, when tyres are labelled 10-ply for example, they are no longer actually constructed of 10 individual layers of cotton, but they do offer the equivalent strength. Over time, steel ply and radial construction replaced cotton, leading to a new distinction: Load Range. Load Range identifies the maximum amount of weight that can be placed on a tyre horizontally, which varies depending on tyre size and inflations limits.