Car and Driver evaluated the properties of tires for crossover vehicles
The American magazine Car and Driver, as part of its test drives, first tested tires of an unusual type, namely models that belong to the All-Terrain category, but were specifically designed for sports cars, usually used only on asphalt and presented in off-road versions. We are talking about the Lamborghini Huracan Sterrato and Porsche 911 Dakar, for which special tires are supplied: Bridgestone Dueler All-Terrain AT002 and Pirelli Scorpion All Terrain Plus respectively.
Bridgestone had previously collaborated with Lamborghini several times and created tires from the Potenza Sport and Potenza Race lines for individual models of the Italian brand, and the All-Terrain AT002 became the company's first off-road tires with a Run-Flat design (reinforced sidewalls withstand the weight of the car in case of a puncture and allow continued movement), developed specifically for a supercar. The tires can be used at speeds up to 270 km/h, and on the Sterrato, they are installed in sizes 235/40 RF19 at the front and 285/40 RF19 at the rear.
"Unlike standard AT tires, which are created with an emphasis on off-road qualities, the tread pattern and sidewall construction of the AT002 had to be refined to increase grip on asphalt during high-speed cornering," notes C&D. "As a result, a kind of Frankenstein's monster was obtained."
The Dueler All-Terrain AT002 has stiffer sidewalls compared to its "classmates" and, in general, borrowed many solutions from the road Potenza Race. The tread pattern with large grooves is optimized for rapid removal of stones and mud from the contact patch, and the unique rubber compound allowed the tires to withstand impressive lateral loads of 0.96 g on the test track (tests were conducted on asphalt). Although the results of other Huracans are generally, according to experts, something extraordinary, the Bridgestone tires still made a strong impression, and for comparison, the semi-slick Pirelli P Zero Trofeo R on the Huracan Performante 2018 can handle loads up to 1.11 g.
The braking qualities of the Bridgestone on asphalt were also impressive, and they were able to stop the Sterrato in 52.4 meters when braking from 113 km/h. For comparison: the Huracan STO on Potenza Race stopped in 46.9 meters, and the Performante on Pirelli Trofeo R - in 41.1 meters.
The Pirelli tires for the Porsche 911 Dakar also showed themselves to be more than worthy and were able to withstand a load of 0.96 g, adds C&D. On the "Dakar" 911, the tires are mounted in sizes 245/45 R19 at the front and 295/40 R20 at the rear, and, interestingly, they, unlike the tires for the Sterrato, do not have the M+S marking.
Porsche says that the engineers were so pleased with the performance of the off-road tires that they made them standard for the 911 Dakar instead of summer tires, and since the optionally available Pirelli P Zero (PZ4) showed a result of 1.04 g on the track (slightly higher than that of the Scorpion tires), it can be said that they made the right choice.
In terms of braking efficiency on asphalt, the difference is roughly the same as that of the tires for the Lamborghini, and if the off-road Pirelli had a braking distance (from 113 km/h) of 49.4 meters, then the P Zero had a distance 5.4 meters shorter. At the same time, when stopping from 160 km/h, the braking distance is reduced by 14.6 meters to 86.6 meters, and, surprisingly, when driving at a speed of 113 km/h, both tires produce noise of the same volume - 76 dB.