Is the Ford Focus RS’ Drift Mode for real, or is it just a quick way to murder your tires? Jeremy Clarkson seems to think it’s the latter. But since I was curious about this as well, here’s what Michelin’s main man could tell me about their special rubber at the Focus RS launch.
The Drift Mode in the Focus RS isn’t black magic. It’s simply the torque-vectoring all-wheel drive system sending the maximum amount of torque to the rear wheels, accompanied by a soft damper setup and the ESP looking away.
It’s fun, and I see no reason why somebody should not drive the car using this setting at all times, but as you would expect, Ford is kindly asking everybody to keep the tail-happy mode to the track. It’s 2016, lawyers are ubiquitous, people can’t drive... you know the drill.
But in order to make the RS disappear in its own cloud of smoke whenever you floor it in first gear at an angle, Michelin had to come up with a Super Sport tire that has all the grip you need on a track, yet will also let it loose when you switch into Ken Block Hero Mode.
(There’s also an optional Pilot Sport Cup2 that’s more track-oriented; both are custom-made for the RS.)
If that sounds like mission impossible, I hear you, but Pierre Chaput, the engineer leading Michelin’s team has a detailed explanation:
Because of the weight of the car (~3,520 pounds) and its 60:40 front/rear weight distribution, we needed to adapt sidewall rigidity.
When all the load is on the front axle during braking, you need a ‘strong’ tire to keep it in control and limit understeer. Yet we couldn’t increase rigidity to the max on the Pilot Super Sport, because that tire also had to be comfortable. Plus, since you have the same tires front and rear, we had to leave some play in them for the drift mode and agility in general.
During our 4 prototype loops and 2000 kms of testing, the idea was to find the good balance between those two goals without compromise.
The case of the optional Michelin Pilot Sport Cup2 tire is different. Since it is going to be used 80% on track and 20% on road, the rigidity of sidewall is on an higher level for maximum track performance.
We use bi-compound technology in both tires.
On Pilot Super Sport, on the exterior side of the tread pattern, we use a soft compound for grip performance. On Pilot Sport Cup2 , this compound has a higher level of grip coming from our competition department (it’s very close to what we use in Porsche N2 at Le Mans) to increase lap time performance. On the interior side of tread pattern, we use a hard compound. We have three goals with this:
The first one is to have steering precision; the second is to have no compromise in wet performance (this compound is very good for wet grip). That’s why we can reach the A label on European regulation on Pilot Super Sport tire. The third goal is to have drift capability. This hard compound has less grip than the exterior compound, so when you start drifting you are going from the external to the internal compound and basically that’s going to help you drift.
Then, you have a 3rd compound on each tire : a small bit just at the exterior shoulder named ‘track longevity patch’. Because it’s the first area in contact with the ground at a curb, we put a specific compound which has a very good abrasion resistance to increase wear life, especially on track duty.
The car needs high pressures because of its weight : 2.8 bars on the front, 2.6 bars on the rear (2.4 bars front and rear for track use). It’s very high for sport tire but we didn’t have any other choice: the car is heavy, and the tires are “small”... I personally would have preferred working with (for example) a 245 in place of 235 to reduce pressure, but the RS doesn’t have enough space for those.
So, in order to keep it under control under all circumstances, we helped the tread pattern to work at this pressure by adapting the aramid belt. This high resistance fiber belt is five times stronger than a steel one. The profile of the tire at high speeds is fully controlled with the tire’s ground footprint staying constant, ensuring maximum grip at all times. With this kind of pressure, we needed to put the exact same quantity of textile on each area of the width of the tread pattern. In a straight line, footprint has the shape of an oval, while in curb, it’s a trapezium.
On the Michelin Pilot Super Sport and Pilot Sport Cup2, you have exactly the same footprint on oval than on trapezium(at +/- 1cm²). That’s what helps you to reach the limit of the grip progressively.
Well, that’s quite some work done for a Ford hatchback. Yet no matter how clever Michelin can get with their chemicals and synthetic fibers, nobody can make a tire that can endure Jeremy Clarkson.
That’s an impossible mission, and always will be.
Then again, he never had to buy one.