Speed rating
The speed rating that the tyre corresponds to.
This indicator determines the maximum speed that tyre is allowed to operate. It is designated by the letters of the Latin alphabet, each of which corresponds to a certain speed limit:
F — 80 km/h; G — 90 km/h; J — 100 km/h; K — 110 km/h; L — 120 km/h; M — 130 km/h; N — 140 km/h; P —
150 km/h ; Q —
160 km/h ; R —
170 km/h ; S —
180 km/h ; T —
190 km/h ; U —
200 km/h ; H —
210 km/h ; V —
240 km/h ; W —
270 km/h ; Y —
300 km/h ;
The maximum permitted speed must not be exceeded — this creates the risk of an accident. However, there are other rules associated with choosing a tyre by this factor. So, ideally, the actual driving speed should be at least 10 – 15% lower than the speed rating of the installed tyres — this will give an additional guarantee in case of emergency situations. In addition, in some tyre models, as the speed approaches the maximum, the upper limit of allowable load is reduced; see “Load Index” for details.
Run Flat
A technology that allows the tyre to maintain its performance even being flat. If a
conventional tyre fails after a maximum of a couple of kilometers with a loss of pressure, then you can drive several tens of kilometers on
RunFlat tyre without any problems — this is usually enough to get to the nearest tyre service. Similar properties are achieved due to the reinforced structure, particularly the increased rigidity of the sidewalls. Different manufacturers may use names other than Run Flat for this technology, such as Flat Run or Zero Pressure.
We note separately, that tyres with this feature can only be used on vehicles equipped with a tyre pressure monitoring system. Without such a system, it is likely that the driver will not notice tyre damage immediately — and this is fraught with several unpleasant consequences at once. Firstly, you can miss the time needed to correct the situation — as a result, the resource of a flat tyre may not be enough to normally get to the workshop or service station. Secondly, driving on a run flat tyre requires slowness and special care, driving in a normal style on such a tyre can lead to loss of control.
Wear resistance (Treadwear)
Tyre wear resistance rate according to the Treadwear standard issued by the US National Highway Traffic Safety Administration.
This rate indicates how far the tyre is able to travel until the tread reaches a critical level of wear. Treadwear is indicated in conditional points; formally, every 100 points correspond to 48,000 km (30,000 miles). However, it should be noted that testing according to this standard is carried out under perfect conditions — on flat roads, without numerous sharp accelerations and brakings, at a stable temperature, etc. Therefore, real wear resistance, usually, is lower by at least 20 – 30 %; and for a full guarantee, the claimed indicator is generally recommended to be divided by two. For example, formally the value of Treadwear 240 corresponds to a mileage of 48 × 2.4=115.2K km — however, in fact it is hardly worth counting on more than 90K km, and it is best to keep on the value of 55 – 58K km.
Generally, Treadwear ratings up to 250 are considered fairly low, 251 – 300 are considered average, 301 – 350 are above average, and over 350 is typical for
the most durable tyre models. Note that this characteristic is given mainly for summer, less often — all-weather tyres; winter tyres should be quite soft, which makes it difficult to achieve more or less worthy wear resistance rating.
