Back home after a superb PCGB track day at Knockhill. The glorious weather, 24c for most of the day, made Knockhill even more special. With an entry of 40 cars there was plenty of space on the 1.4 mile track. A diverse selection of Porsches were represented, including several 991.1 991.2 GT3 RS's, and a 991.1 Carrera Cup car. There was also a Radical sport racer doing a few shakedown laps during the quieter afternoon session. With a few track day newbies present, there was a problem early on in the morning with some of them not giving way to faster cars. Following words with Steve Kevlin this was soon sorted out.
The resurfaced track and new kerbing profiles are a big improvement to Knockhill. The kerbs are smooth and grippy and are there to be used to maximum effect. With track temperatures being so high, tyres pressures had to be adjusted accordingly. I started off with 32psi and had to lower the pressures to 29psi as the hot conditions made on-track tyre pressures soar.
This Knockhill event was my first properly dry track experience with the new Michelin PS4S N0 tyres. So, what is my verdict?
To say I was disappointed would be putting it too strongly. Shall we say it was more a case of the PS4S N0's falling somewhat short of my expectations. Having had previous track experience with Michelin Pilot Sport Super Sports on my CR, at Silverstone GP circuit no less, I was hoping the PS4S N0 would offer an improvement in durability of grip over it's highly respected predecessor. Not so I'm afraid to say. On this hot day at Knockhill, the PS4S N0's would provide no more than 3 hot laps at motorsport pace before going all slidey, just like the Pirelli P-Zero N1's did last year on the same track, albeit in cooler ambient conditions. I expected more high speed performance by way of grip durability from the new PS4S N0. The G-Force readings recorded on Sport Chrono we're not all that impressive either. At the same track last year on P-Zero N1's I recorded a maximum of 1.38 lateral G, compared to 1.31 lateral G recorded this year on PS4S N0's. Not what I wanted to see. In my layman's opinion, I would say the dry grip durability problem lies in the tread compound and sidewall construction being focussed more on wet weather performance. The PS4S N0 is predominately a road tyre, Michelin say 80% road, 20% occasional track use. I would say it's more like 95% road and 5% track, in hot dry conditions that is. In the wet, on a track, the PS4S N0 is the best wet weather tyre I have ever experienced, period. In streaming wet conditions the grip is truly astonishing, let me be absolutely clear about that. I'm just sorry Michelin have chosen to trade-off some dry weather grip in favour of wet weather performance. I'm not saying the PS4S N0 is a bad tyre, far from it. For general road use, at road legal speeds, and in all weathers, the PS4S N0 is an absolutely top class premium tyre. However, for experienced track day exponents such as myself, they are nothing to write home about. Michelin Cup 2's are the tyres I would fit next time for my track day exploits. The parting shot? Michelin Pilot Sport Super Sports are the better tyre for general road and occasional track day use by being more durable in sustaining grip levels consistently in dry conditions. In my opinion I can't be fairer than that.
Brian
