Classification of Tyres by Type of Road Surface
Once in a while, every car owner needs to mount a new set of tyres, whether it pertains to premature wear of tyres, seasonal replacement or other causes. Choosing tyres should be approached as responsibly and seriously as possible, as this is the only way to ensure driving safety and comfort in specific conditions. Thus, one should pay due consideration to the type of tread pattern. At the same time, the environment in which the tyres will be operated is no less important. We suggest considering the classification of tyres, depending on the type of road surface.
Types of Automobile Tyres
Based on operating conditions, automobile tyres can be divided into the following types:
Let us consider the features of every type.
They are marked with HT or HP symbols (Highway Terrain and Highway Performance). Such tyres are designed primarily for driving on hard surfaces, have good traction on asphalt road, minimal noise level, and effective water removal from the contact patch. At the same time, highway tyres feature mediocre self-cleaning characteristics of the tread pattern from dirt, stones and other small debris, having poor off-road properties. The use of such tyres in winter on snow- or ice-covered roads is unacceptable since their grip characteristics in such operating conditions are significantly worse compared to winter and all-season tyres.
HP and HT Modifications have some differences. Thus, tyres marked with Highway Performance are intended primarily for driving on asphalt, and Highway Terrain models can be used for driving on hard surface roads with poor quality surface and earth roads. At the same time, the HT version loses in speed characteristics: such tyres are designed for driving at speed up to 180 km/h (S index), while HP tyres can reach the speed of up to 210 km/h (H index). Usually, highway tyres have an asymmetric tread pattern.
Such tyres are marked with MT symbols (Mud Terrain). These are special-purpose off-road tyres, ideal for driving on rocky roads and deep mud. They have a tread with deeper lines and large blocks (with no lamellae in the design); the distance between blocks is made larger to guarantee high-quality self-cleaning.
Some mud tyres are equipped with so-called lateral lugs (the tread is partially transferred from the shoulder area to the sidewalls), which ensures increased traction when driving on mud roads. The main disadvantage of mud-terrain tyres is the increased noise level and relatively low braking performance on asphalt. Typically, mud tyres have a low speed rating (the maximum possible acceleration speed is 160 km/h, which corresponds to the R index).
These tyres are marked with the symbols AT (All Terrain) and intended for any surface: dry or wet asphalt, dirt roads and rocky gravel roads. These tyres have a relatively low noise level while ensuring excellent off-road properties and driving comfort. The tread of AT tyres has a more aggressive pattern compared to highway models (larger blocks, greater distance), which provides better self-cleaning from dirt.
Such tyres are marked with ST symbols (Sport Terrain) symbols; according to the classification, they occupy an intermediate position between HT and AT. These tyres are primarily designed for an active driving style. Sport tyres have a good performance on asphalt, good cross-country and off-road ability in non-extreme conditions. Sport-terrain tyres are recommended for use in the urban driving cycle with periodic trips out of town. These tyres are a kind of hybrid of the highway version, which features a medium-sized and non-aggressive tread in the central part (for a low noise level), and a rather large and developed shoulder blocks (for a comfortable ride off- road).
Having studied the features of all tyre types, we can come to a logical conclusion: the more aggressive the tread pattern and the lower the speed index, the better off-road properties the tyres have. And with an increase in off-road qualities, noise level increases as well, leading to a lower ride comfort. That is why everyone should decide for himself, what compromise he would agree to when choosing tyres for the specific operating conditions.