Quote:
Originally Posted by conradb58
You have driven on the Nordschleife by your F80 picture and you know in the car park that if other drivers are not on a semi-slick they are on a PS4S
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They aren’t bad tires at all, and BMW has some interesting formulations on their recent M cars that are measurably faster on track. I’m guessing even as much as 6-7 seconds on the Nordschleife. In the US, I am using these as daily drivers and rain tires for track, and carry slicks on the rear seat for dry weather track work.
That said if you are really fast, the PS4S are not a good choice. They have a narrow optimal temperature operating window of about 10 min (plus minus, depending on track, temps, driver etc) after which as you have noted they become greasy. But that isn’t the biggest issue. It’s that as you drive quickly, the super-special-secret-sauce Michelin soft outer shoulder compound (which gives it such nice cornering capabilities) is the first to wear away. Such that by half day (or full day) the outer shoulder is literally gone, and the tires unusable. Michelin uses this technique of a soft but grippy outer shoulder compound on other tires, including the Cup2. Which is why even the Cup2 is not a perfect choice for track tires. My friends who run GT3 and GT3 RS’s have found this to be true as well, so it isn’t a BMW problem.
Not driving on PS4S on track is as much a function of chasing better times as it is a function of not destroying such expensive tires without much benefit.
This wear pattern can be reduced by increasing the front negative camber (perhaps via camber plates) but it will only take you so far. BTW the rear tire wear is much better/more even, BMW has nailed that part since the F8x generation.
There are better, more durable tires for track work. I would favor durability over reduced lap times anyway, as a sound driver development tool. Durability and progressiveness is where you begin tire wise. What you want is consistent lap times for 30 min at a stretch, so that you can concentrate on learning the other 100 things you have to master on track.
Free advice here, hard earned over 20 years of track experience and expenses. You don’t have to take it, but soon enough if you keep tracking the car you will be back here telling us about the incredible wear on the PS4S.