Comparison Triangle TR968 255/30 R22 95V vs Powertrac SnowStar 215/50 R17 95H

The time of the year the tyres are designed for.

Tyres designed for the warm season are called summer, for cold — respectively, winter (among the latter, studded and non-studded models are separated, see below for details). The need for separation by season is due to the fact that when the temperature drops, the rubber solidifies; therefore, cold weather requires softer tyres than warm weather. And the time when you need to change tyres is best determined by the average daily temperature: if it is above +5 °C, it is better to use summer tyres, if lower — winter ones. There are also more detailed recommendations regarding the time of changing tyres, they can be found in special sources.

Also note that there are tyres positioned as all-weather. Such models should be treated with some caution: they can be produced in countries where winters are very mild, without snow and severe frosts, and be designed specifically for such “all-season”; for a full-mean winter, such tyres may not be suitable. So the specific attributes of all-season tyres should be specified separately (including reviews). If there are no detailed info, such tyres are best considered as summer tyres with slightly increased resistance to cold, and if used in winter, then in simple conditions (for example, driving along well-cleaned city streets).

Tire section width is the distance between the sidewalls of an inflated but not loaded tire. As a rule, this parameter is indicated in millimeters, but there are also inch designations for the profile width.

Width is one of the characteristics that determines the compatibility of a tire with a specific wheel (the second characteristic is the mounting size). It is worth noting that the width of the tire does not have to strictly correspond to the width of the rim; certain deviations are allowed. There are special tables that allow you to determine the permissible width values for a particular wheel; in addition, such recommendations may be indicated in the documentation for a specific car.

The following tire width options are available on the modern market: 135 mm, 145 mm, 155 mm, 165 mm, 175 mm, 185 mm, 195 mm, 205 mm, 215 mm(in inches this is 8.5”), 225 mm, 235 mm, 240 mm(in inches this is 9.5”), 245 mm, 255 mm, 265 mm(in inches this is 10.5”), 275 mm, 285 mm, 290 mm(in inches this is 11.5”), 295 mm, 305 mm, 315 mm, 320 mm(in inches this is 12.5”), 325 mm, 335 mm, 345 mm(in inches this is 13.5”) and over 345 mm( over 13.5”).

Tyre aspect ratio. This parameter is usually expressed as a percentage of the width, since it is not the height itself that is of practical importance, but its ratio with the nominal section width.

In general, the lower the ratio, the more stable the tyre, the better it is suitable for high-speed driving on flat roads. Higher ratio, in turn, work better on rough surfaces and over obstacles, making them good for bad roads and off-road. If we talk about specific numbers, nowadays, the following options are spread on the market:

— Low profile tyres: 25%, 30%, 35%, 40% ;
— Medium profile : 45%, 50%, 55%, 60% ;
— High profile : 65%, 70%, 75%, 80%, 82%, 85%, and 90% or more.

Tyre inner diameter in inches. The key parameter that determines the possibility of installing a tyre on a car: the tyre diameter must match the diameter of the rim. It is worth noting that some vehicles have +/- 1 inch diameter tolerance; this point should be clarified separately in each case.

In modern passenger vehicle tyres, the following rim diameters are most widely used: 12", 13", 14", 15", 16", 17", 18", 19", 20", 21", 22", 23", 24".

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.

The shape of the tyre tread pattern:

— Directional. Pattern with a characteristic V-shape. Among other things, such rubber is considered to be especially effective on wet surfaces — in rain, on snow, with an abundance of melt water, etc.: the pattern provides effective water drainage, reducing the risk of hydroplaning and increasing grip. Also, these tyres are well suited for high-speed sports cars (although, of course, their speed rating and specialization may be different). When installing directional tyres, the direction indicated by the manufacturer must be kept.

— Symmetric. The pattern without signs of directionality is the same both on the outer and on the inner part of the tread. These tyres are easier to manufacture than directional or asymmetric tyres, and are generally cheaper, while still having good performance on a flat and dry surface. In addition, symmetric tyres are as simple as possible to install, they do not need to follow the direction. However, for hard conditions, particularly wet weather, they are poorly suited. So, typically, such tyres are designed mainly for city cars used on short trips on relatively high-quality roads.

— Asymmetric. Tyres with a different pattern inside and outside the tread. Each of these parts plays a role: the inner part provides water evacuation and reduces the risk of aquaplaning, while the ou...ter part provides the necessary rigidity for manoeuvrability and stability. While installing, you need to take into account the location of the outer and inner sides, they usually have the appropriate marking. Asymmetric tyres are considered the most advanced, although, of course, the actual characteristics and cost of such products may vary, depending on the brand and the general level. Such tyres are designed mainly for cars of medium and top levels; they are often supplied as factory equipment for advanced cars.

The rolling resistance rating that the tyre corresponds to. The higher this figure, the lower the resistance, the less fuel is spent to overcome it and the more economical the tyre is. Efficiency indices are denoted by letters of the Latin alphabet in descending order of efficiency: A(highest efficiency), B, C, D, E, F, G(lowest efficiency).

With other things being equal, more economical tyres tend to cost more, but the difference is offset by fuel economy.

An index that determines the overall performance of a tyre on wet pavement. Lettered from A(highest) to G(lowest); intermediate options, respectively — B, C, D, E and F.

The higher this indicator, the stronger the tyre grips to the wet road, the more efficient and safer it will be in difficult weather conditions. At the same time, it is worth noting that a low grip index does not mean unsuitability for driving in rain or snow — you just need to be more careful using such tyres. Conversely, a high index does not relieve the driver of the need to be careful in difficult weather conditions.

The average noise level created by a tyre while driving. The lower this indicator, the more comfortable this model will be, the less additional noise it will create.

Note that EU rules provide 3 categories of tyres in terms of noise. “Quiet” are considered models with an index of up to 68 dB, “medium” — 68 – 71 dB, “loud” — 72 dB and above.