Tyre Speed Ratings

One of the most commonly-asked questions is “what do the speed ratings mean”?. Below is an explanation as published by Dunlop.

WHAT DOES ‘SPEED RATING’ MEAN?

‘Speed Rating’ is the speed which a tyre can withstand constantly without flying apart. It is measured by running a tyre, under loaded conditions, against a large drum. To meet a particular speed rating, the tyre is run for periods of time at different speeds according to the standard (whether European or American).

Illustrated below are common speed ratings and their ‘speed symbol’:

Tyre Speed Rating

This speed rating must be moulded onto tyres’ sidewalls to comply with the relevant standard. Below are 2 systems of tyre branding in current use:

Tyre System Chart

New car manufacturers are required to fit tyres that can match the car’s top speed for obvious reasons. The same used to apply for replacement tyres, but now this is changing. In Australia, replacement tyres must only meet a minimum of ‘S’, which is 180 km/h, or 70 km/h above the maximum legal speed in any state.

It is important to understand that speed rating is not an indication of road handling performance in any way. In fact, most methods of raising a tyre’s speed rating can have the reverse effect. However tyres made for vehicles with high speed capabilities tend to also require high performance characteristics as well.

Producing tyres with high performance characteristics and speed ratings is expensive.