MORE ACRONYMS, FEWER DOWNSIDES: Sharkskin and Other Technologies Improve Performance Tire

by Joe Kovach

AutoWeek Magazine
April 30, 2001
P. 5

"Tire makers continue to improve performance tires but now they're avoiding traditional downsides, such as poor handling in wet or snowy conditions, short tread life, and road noise.

Bridgestone unveiled its latest version of such a tire at the Jerez Formula One track in Spain: the Potenza S-03 Pole Position. It replaces Bridgestone's top street-performance tire since 1995, the S-02. The S-02 has been original equipment on the Aston Martin DB7 Vantage, Ferrari F360 Modena and F550 Maranello, Honda S2000, and Porsche Boxster, 911 and 911 Turbo. Bridgestone hasn't confirmed any OE fitments for the S-03 yet.

We sampled the S-03 at the F1 track, driving BMW, Audi and Mercedes street cars, rode with professional test drivers, and maneuvered an autocross course. John Rastetter, tire information director for the Tire Rack, who also attended the intro, described the S-03 as 'a more civilized version of the S-02 and some other similar tires in this category.'

Bridgestone also displayed a Ferrari F1 race car and one of its rain tires, unmounted. The tire was so light and soft that you could fold it up with your hands. The street tire isn't so soft and light, but uses some of the F1 rain tire's technology. Both the F1 and S-03 use H.E.S. (Hydro Evacuation Surface), which is sharkskin technology, also employed by NASA and in swimsuits that allow Olympic swimmers to glide through the water better. The water channels aren't the traditional smooth, straight design, but feature little protuding angles allowing for better water flow and drainage. Traditional straight channels, Bridgestone says, cause more turbulence (tiny, choppy waves) than the sharkskin-style channels.

Acronyms abound in today's tire technology. C.S.C. (Consistent Surface Contact) is also borrowed from the F1 program, and allows for more uniform contact pressure. The typical contact patch has the highest concentration of pressure on the edges, descending to almost none in the center. By changing the geometry of the tire, pressure is distributed more evenly. Throw in Super L.L. Carbon (longer carbon links to improve wear-resistance) and the diabolical-sounding Particle Z (provides better grip in the wet than silica) to the dark science of mixing tire compounds.

Bridgestone says a new tread-on-tread design (Dual Layer Tread II) provides more consistent performance in the wet as the tire wears. While the old S-02 used a dual-layer tread, the second layer of tread was not exposed until part of the outer tread layer wore away. On the S-03, the second, more gripping tread compound is exposed in the center of the tire when new, and that exposure is gradually widened from the center outward as the miles escalate.

The S-03's UTQG (Uniform Tire Quality Grading) treadwear rating is 220, vs. 140 for the old S-02. Rastetter estimates enthusiasts would get 25,000 to 30,000 miles out of the S-03. It will be available in May in 51 sizes, from 15- to 20-inch diameters.

Another new high-performance tire is the Pirelli P7, names after its progenitor from 1974. The original P7 evolved into the P700, P700Z and P7000, but, as a spokesman noted, Pirelli decided against calling its newest version the P70,000.

Pirelli says its engineers have strengthened the new P7's rigidity while making it lighter. A thinner but high-tensile steel belt and a nylon belt with "new Nylon 0" make the tire more rigid. That, along with a new rib and groove design and stiffer shoulders, enhances braking and cornering capability.

Like the Bridgestone S-03, the P7 features a footprint with more uniform contact pressure. Besides the performance benefits, it improves rolling resistance and provides 10 percent more even wear vs. the previous tire. With help from four longitudinal grooves, the new, wider contact patch also resists hydroplaning better.

P7s are scheduled to start arriving in the States soon, and Pirelli says the tire is in the OE approval process for makes such as Audi, BMW, Mercedes and Volvo."

 

Despite what the article says, this does not seem like a direct replacement for our stock tire. It describes more like a replacement for the current pole position. Am I misunderstanding?

 

It looks like a SO-2 PP replacement to me also. Awear rating of 220 vs. 140 for is not going to be a better dry track tire.

 

It's also telling that there are no OEM contracts with auto manufacturers for the tire. I suspect they'll make a higher performance W rated versions for the OEM's if the requests come in.

I didn't realize the S02 was the OEM tire for so many cars. But this confirms my suspision that S02's will have to be manufactured for quite a while yet.

 

[QUOTE]Originally posted by ScottB
[B]Despite what the article says, this does not seem like a direct replacement for our stock tire.

 

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