Vehicle’s moving on the road surface cannot be noiseless what is conditional on the physics laws. Although summer tires create less noise than winter tires, the former also ensure unpleasant sound. That’s why noise factor today is as important as hydroplaning resistance level and braking performance. Of course, tire noise level depends on the road surface type and tire pressure level. If road surface is patchy and pressure level does not conform to the vehicle manufacturers’ requirements, noise level will obviously rise. Nevertheless, a lot depends on the rubber compound, tread pattern and tire width. For example, tires that are manufactured with the use of soft rubber compounds and have comparatively small contact patch reproduce considerably less noise. Reduced noise level provides riding smoothness and makes steering more comfortable for a driver.
In spite of growing consumer demands in the sphere of tire noise reduction tire manufacturers activate the work in this field for another reason. The thing is that many ecological organizations as well as separate states have got seriously concerned about the problem of noise on the roads. For example, European Federation for Transport and Environment offered European officials to consider the issue. According to this respected organization considerable part of noise on the roads is caused not by the engine sound but by the sound produced by rubber that contacts road surface. Even at 20mph speed the level of tire noise of passenger cars exceeds the noise level produced by the engine. Taking into consideration growing demand for wide tires the problem is becoming more vital. That’s why it is expected that new regulations of the European Commission that are to come into force on November 1, 2011 will contain tire noise requirements along with the regulations on wet traction and tire marking. Such state of affairs makes tire manufacturers develop new models that provide reduced noise level.
How can one reduce noise level produced by a tire when contacting the road surface? Noise level is influenced by such parameters as tread pattern, studs and sipes design as well as rubber compound peculiarities. Each contact of a separate tread block with the road surface causes noises of a definite frequency. If all blocks have the same size they will produce noises of the same frequency what in its turn will lead to the general noise level increase. That’s why many manufacturers use blocks of different size in separate tread areas thanks to which tire noise is allocated in a wider frequency range. Such design peculiarities allow to reduce general noise level.
Special tire tests allow to determine noise level and, correspondingly, driving comfort. As a rule, they are conducted in combination with tests on braking performance on dry and wet surface, hydroplaning resistance, etc. The measuring of the produced noise is determined in dB, at the right and at the left side of a vehicle. The vehicle’s speed is also being registered.
We offer You tests of summer tires (205/55 R16) conducted by our specialists. The testing was conducted in respect of steering control on dry and wet asphalt, directional stability, fuel consumption level, riding comfort and noise level. Eleven summer tires participated in the tests: Pirelli P7, Michelin Energy Saver, Nokian Hakka H, Yokohama C. Drive AC01, Maxxis Victra MA-Z1, Goodyear Excellence, Kumho Ecsta HM, Bridgestone Potenza RE001 Adrenalin, Continental ContiPremiumContact 2, Toyo Proxes CF-1 and Vredestein Sportrac 3. The experts evaluated tire noise level as well as other characteristics. 10-point scale was used.
The experts gave the lowest mark to Korean tires Kumho Ecsta HM – six from ten. Such a low mark is connected with serious overall noise, tread howl at speed up to 50mph. The howl, however, disappeared at a higher speed.
A few tires got an average mark seven from ten. In particular, Maxxis Victra MA-Z1 tires took the last place in test due to increased consumption level at all speeds and abrupt pushes when riding through undulations. It also had increased noise level. Even innovative flame-shaped tread pattern of Maxxis Victra MA-Z1 wasn’t able to help. Summer tires Yokohama C. Drive AC01 make too much noise when cornering. At 75mph speed and higher the tires loudly clap on seams and other undulations in spite of the application of new “Micro Flexible Compound” that, according to the designers, is to provide minimal noise level. That’s why the experts gave only seven points to Yokohama. The same mark was given to Potenza RE001 Adrenalin – a high-speed summer tire with an asymmetric tread pattern. On single undulations they push the vehicle sharply and produce respective background noise. Continental ContiPremiumContact 2 tire distinguished by three-dimensional grooves and flat edges also showed average noiselessness level. The tire produces increased background noise, especially on a hard-grained surface. ContiPremiumContact 2 ensures high level of comfort on a good road surface, but it produces unpleasant noise when riding through average and large undulations. The result is seven from ten. Michelin Energy Saver summer tires provide high fuel efficiency at high speeds but the produced noise level depends on the asphalt granularity. On dry asphalt they have a little bit increased noise level. The same result – seven from ten. Vredestein Sportrac 3 summer tires showed excellent steering control and braking performance. The experts noted unpleasant background noise that provides insufficient level of comfort.
Four models received eight points and became the best in respect of noise level. Goodyear Excellence tire features a sequence of double-step blocks what allows to reduce noise level. According to test results Goodyear showed low noise level and high riding comfort. High mark was given to Pirelli P7 with an asymmetric tread pattern. Despite of high fuel consumption rate the tire provides high comfort level. It is extremely quiet and gives only slight feeling of undulations. Noikan Hakka H took the third place and also showed good comfort level. These quiet comfort tires allow to feel slight pushes caused by undulations only at a “pedestrian” 5mph speed. Further acceleration makes the tire practically noiseless. The mark is eight from ten. At last, Toyo Proxes CF-1 that replaced Toyo Proxes R610 was distinguished by extremely high acoustic comfort that was marked during the tests.
The conducted tests show that summer tires with excellent steering control both on dry and wet surface, high treadwear resistance level and superb directional stability can be distinguished by increased noise level (Vredestein Sportrac 3). At the same time tires with average steering and braking performance can get the highest marks in respect of noiselessness (Goodyear Excellence). It means that the choice of summer tires should depend not only on one specific characteristic but on the whole set of properties including performance on wet and dry surface, directional stability, hydroplaning resistance level, acoustic comfort level, etc.
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