All-Season Tires for the ATS-V
Michelin Pilot Sport All-Season 3+
By Hib Halverson
For the last several months, the V-Net staff has been evaluating the Michelin Pilot Sport All-Season 3+ on one of our ATS-Vs. We decided to undertake this test because there are ATS-V owners with cars serving mainly as “daily drivers” who desire increased tire tread life. There also owners who drive their V’s in places which see cold wet weather and occasional snow and want an improvement in traction in the cold and wet.
The OE tire on an ATS-V is the Michelin Pilot Super Sport, 255/35ZR18 in the front and 275/35 ZR18 at the rear. Interestingly, Cadillac chose the non-run-flat version, perhaps to take some harshness out of the car’s ride. The “PSS” is categorized as a “Summer” tire and that’s one reason the ATS-V has outstanding dry handling and reasonably good wet handing when driven in hot, warm or cool weather. The PSS is, also, a good choice for occasional track use, given proper tire pressures and suspension alignment. Brian Remsberg, Director of Consumer Public Relations for Michelin North America told the V-Net in an interview, “Summer tires are primarily for high-performance cars, such as the ATS-V. They provide outstanding dry and good wet performance levels in a temperate environment. Summer tires are not designed for winter use where temperatures are colder (40°F or less) and approach freezing on a regular basis. In those conditions, their performance will be less than optimal. Additionally, summer tires may not have as long a tread life as would an all-season tire designed for a standard passenger car, SUV or light truck.”
Of the two ATS-Vs we have, the Crystal White Tincoat four-door we call “Pearl”, has the most miles on it and gets driven more in cool, wet weather than our ATS-V two-door. Also, Pearl sees a lot more use typical of daily drivers. We asked Remsberg what Michelin tire would be good on an ATS-V for “light winter” driving and longer tread-life. He suggested the new “Pilot Sport All-Season 3+”. “All-season tires,” Brian continued, “are the most popular tire on the road. They are engineered to handle ‘everyday’ driving conditions. An all-season tread provides balanced dry and wet performance level in both temperate and cool weather, as well as acceptable snow traction in regions with light winter weather. All-Season tires are a practical solution designed for year-round use and, typically, have a longer tread life.”
Michelin press info says the Pilot Sport A/S 3+ benefitted from Michelin’s successes in endurance road racing and the company’s technological innovations in four areas. First, is Michelin’s “Helio+” tread compound combined with biting edges in the tread grooves that grab loose snow. Both those features enhance acceleration and braking in “light winter” conditions. Another is the use of silica in the tread compound, a feature developed for endurance road racing rain tires. Silica, along with variable thickness sipes and large circumferential grooves, result in good wet grip and resistance to hydroplaning in deep water. A third is “Variable Contact Patch 3.0”, another feature that came out of endurance racing, which distributes cornering forces and tread temperatures more evenly through the patch of tire tread which contacts the road. Lastly, the A/S 3+ has an asymmetric tread pattern inspired by the Pilot Super Sport. The result is satisfactory dry grip, great wet grip, good performance in light snow, and better tread life.
In 26,519 miles, we burned though Pearl’s rear Pilot Super Sports. This was not self-inflicted with burn-outs, either. Our ATS-V four-door came out of Lansing Assembly with incorrect rear suspension alignment. We did not discover the problem until about the 18,000 mile mark when we started to hear tire noise and noticed the rear tires were wearing much more rapidly than were the fronts. The higher tread wear was due to the rear toe adjustment being incorrect. At that point, we had the rear alignment reset to the proper specs. The rate of wear of the remaining tread decreased, but the damage was done. By 26,000-mi, the “wear bars” on the rear tires were showing and 500 miles later, we replaced all four, discarding the worn out rears and saving the fronts, which still had plenty of tread, as spares.
Based on what Michelin’s Brian Remsberg told us and willing to compromise a little at-limit handing for better tread life, since our dealer, Bunnin Cadillac of Santa Barbara, is also a Michelin Tire retailer; we ordered a set of Michelin Pilot Sport AS3+s for Pearl. This tire is Michelin’s premium all-season tire for performance cars.
For the V-Net’s sister web site, the Corvette Action Center, several times we’ve interviewed Lee Willard, one of Michelin’s top tire engineers. When it came time to learn a little about the “PS AS3+” we sat down with Brian Remsberg and Lee Willard for a little Q-and-A. Our first question was about the starting point for the product’s development. “It (AS3+) came out of the Pilot Sport All-season 3,” Willard said. “While they have the same tread pattern and similar internal architecture, there was a significant evolution in the tread compound. It is optimized to maintain a good level of dry grip but have improved performance on snow.”
“The really cool thing about that tire,” Brian Remsberg added, “is that, jumping from the AS3 to the 3+, there was a 28% improvement in traction on snow. There were no changes to the tread pattern. It was all in the compound.”
“A groundbreaking technical feature of the Pilot Super Sport is that we designed the mold shapes using the same software we used in (making) racing (tires),” Lee Willard continued. “We use this software to optimize the contact patch to even out stress distribution. The first (street tires) where we applied the race tire optimization software were the Pilot Sport Cup 2 and Pilot Super Sport. Then, we took that software and applied it to an all-season tire, so you had racing level–Formula 1 and Le Mans–computer optimizations run on the tread patterns, mold shapes and contact patches used for the Pilot Sport All-season 3+.
“Beyond that, the internals of the tire–the carcass, steel belts and belt angles–are much the same as the Pilot Super Sport. An all-season tire usually has 8-8.5-mm tread depth where the summer tires are 7.5-8-mm tread depth. The belt package and the cap ply on the AS3+ are engineered to hold a tread which is a little bit deeper–under both centrifugation (changing of the tire’s shape at high speed due to centrifugal force) and in cornering.
The folks at Bunnin Cadillac mounted, balanced and installed the PS AS 3+ tires on Pearl then sent us on our way. At this writing, the tires have been on the car for about eight months. So far we’ve noticed that, indeed, compared to the OE Super Sports, these tires have slightly less dry grip in warm weather. Michelin’s Lee Willard told us that, on an ATS-V, it’s less than a tenth of a “g” difference–0.98-1.00g vs 0.90-0.92g–on the skid pad. For an all-season tire, 0.90g is outstanding. Because the ATS-V’s chassis was designed for the Pilot Super Sport and the PS AS3+ is so close to the PSS, steering feel is much the same with both tires except when you near each tire’s limit. At the limit, the two don’t feel quite the same–we attribute that to a little more tread “squirm” due to the AS3+’s more and deeper tread grooves. In a given turn, with the AS3+, we had to hold a little bit more slip angle because of the tread squirm. In cool weather, it was easy to spin the PSSes on hard acceleration from a stop or a slow roll. The AS3+ tires are not as easy to spin when cold. We didn’t get this test started soon enough in 2017 to have a chance to test the Pilot Sport AS3+ in wet weather and that was unfortunate considering the rain Southern California had during the winter of 2016/2017. We will update this product evaluation as time goes on and we get into the winter of ’17/’18.
Also, once we get a fix on the trend in tread life, we’ll report back on that, too, however Lee Willard told us that Michelin’s wear testing indicates the average ATS-V driver will get 25,000 miles or so with the Pilot Super Sport. With the All-season 3+, Willard said you can probably add 7,000 or 10,000 miles to that, however, he added the disclaimer that wear testing is done in South Carolina. Wear rates are higher in the east and southeast than they are out west because eastern road surfaces have a higher proportion of granite which is more abrasive than the surfaces used out west which have a higher proportion of less-abrasive limestone.
Lee Willard also talked about how wear rates of tires differ with temperature. “The tire industry recommends not using summer tires in 40°F or below weather, ” Lee stated. “This is because the rubber is optimized for warmer temperatures and wears faster at cooler temperatures. If you drive a summer tire when the temperature is around 40° or less, you’re going to wear that tire out probably 30-40% faster than if you’re driving on roads at 70-80°F. It’s a characteristic of the various polymers used in summer tires and the way they work.
“When the rubber in a summer tire gets cold, it gets harder,” Willard continued. “When it becomes harder, it chips away–it wears away faster, but in summer temperatures, it’s going to be more optimal–it’s softer and doesn’t wear so fast.
“The same principle, but in an ‘opposite direction,’ applies to all-season rubber,” Willard added. “In cool and warm temperatures, it is going to last longer, but drive an all-season tire in extreme summer weather, such as the desert southwest in August, and it will wear faster. It’s so warm for the temperature range of that rubber in the tread compound that the rubber stretches and strains. The (rubber) molecules are literally ripped away–the tire wears faster.”
Again, we are running this test in California where average daily temperatures are seldom near 40°F. What we want with the Michelin Pilot Sport AS3+ is better wet traction during “California winters”. We’re also looking for that 30% or so improvement in tread life.
Thanks to Lee Willard and Brian Remsberg for assistance in preparing this review.
For more information on the new Pilot Sport AS3+ tire take a look at Michelin’s web site at http://www.michelinman.com/US/en/tires/products/pilot-sport-a-s-3-plus.html