Carl Driver is a senior product development engineer at Michelin. He graduated from Clemson University with a bachelor’s of science degree in mechanical engineering and started at Michelin 12 years ago. He’s been with ultra-high performance (UHP) tires for six years. Previously, Driver worked on truck tire design after starting his career at Michelin in the retread area of truck tire team. We sat down with Driver to discuss the new Michelin Pilot Sport 4S.
What did want to improve on Pilot Super Sport with the new Pilot Sport 4S?
Carl Driver: First, the name Pilot Sport 4S (PS4S) is because it’s a part of the Pilot Sport family (and the fourth-generation Pilot Sport UHP tire). The PS4S is the replacement for the Pilot Super Sport (PSS). We had some pretty demanding requests from product marketing. They wanted better dry/wet braking, lap times, and rolling resistance. Remember, rolling resistance is now a threshold in Europe—if you don’t meet it, it doesn’t sell. They also wanted to maintain wear—the 30,000-mile warranty. Take everything we had with the PSS and expand it. That’s the PS4S. Only the wear characteristics stayed the same, equal to the PSS with a 300 tread-wear rating.
What are the key technologies and developments at Michelin that allow these improvements?
CD: The PSS has consistently ranked number one in tests and comparisons over the past six years. How do you improve upon the best? It’s incremental (advancements) in many areas. For example, materials. We’ve also played with the sculpture. We’ve taken some design features from the Pilot Sport Cup 2 (track-focused tire). The tread pattern is very similar, for example. Internally, the architecture allows us to get the high-speed characteristics—the handling and cornering. It’s taking the technology from the newer tire like the Cup 2 or just improving on what we’ve had in the PSS. The advancements aren’t much individually but added together, the tire package is able to achieve the goals set by product marketing.
What was the timeline for PS4S development?
CD: A new tire line generally begins two years before launch. We’ll develop a tire for one or one and a half years. After we’ve passed the milestones where we’ve met the targets for marketing, we’ll start industrialization. That’s usually about a year. We’re launching the PS4S in March (in the U.S., Europe was January) with 35 sizes. It takes about a year to get all the inventory, the molds ordered, regulatory testing, etc., that has to be done for each individual tire. You also have to get the inventory, the warehouses, and distribution ready.
What have been some specific challenges with the development of the PS4S?
CD: It’s about taking the base tire and how do we go about increasing everything. It’s called Michelin Total Performance. How do you advance wet/dry handling and braking? How do you improve rolling resistance and decrease wear? With the materials and the sculptures, we were able to get better rolling resistance but maintain or improve wear. In the past, those have been paradigms. It’s breaking that paradigm. There are more than 200 elements we can change when developing a tire. Michelin Total Performance is now stamped on the tire to back up our claims.
Tell us more about FIA Formula E as well as other racing correlations to the PS4S.
CD: Formula E wanted a tire that was relevant in size and design to a street tire, but it also had to perform well on the track. The sculpture of the PS4S is almost identical to the tire that was on the Formula E car in the first two years. Michelin doesn’t do racing as a marketing exercise, we take what we learn at the track and apply it to street tires. The Le Mans 24 program also really helps with the compound side of things. The elastomers (rubber) we developed in racing carried over to the street tires. To be able to triple or quadruple stint a tire (at Le Mans) is pretty amazing. There is also the aramid (Kevlar) correlation. That’s straight from endurance racing.
What is a customer going to feel when they drive a car fitted with the new PS4S tire versus the PSS?
CD: They’re going to notice a difference compared to the PSS right away. It’s a step ahead of our competitors as well as our own tire line. Handling—the level of grip and lap times—is better. Also, they’ll have more confidence going into a corner compared to the PSS. Braking, for sure, both wet and dry braking. I don’t think they’ll notice rolling resistance, but that’s improved.
Has the PS4S reached a level of performance so a person who mostly drives on the road and isn’t a hardcore track person but wants to play on a circuit will be happy? They don’t necessarily need to buy a track-focused tire like the Pilot Sport Cup 2.
CD: It really has. You can drive the PS4S every day, but if you want to have fun on the weekends for a track day at your local club, it’s a great tire. You don’t have to bring two sets of tires. You can drive to the track (on the PS4S), have fun, and then drive back home. It’s important to note that when you are tracking the PS4S to follow the recommended tire pressure settings. Hot pressures should roughly be similar to the recommended cold pressures for the street. Just make sure to change back to the road pressure settings before you leave the track. The PS4S and the Pilot Sport Cup 2 both have a similar theory on track pressures. It’s preference and driving style, but in general mid-30s psi (hot) is recommended. A lot of people track the PSS, and they’re going to see improvements in lap time with the PS4S.