Trackday Tyre Pressure.?

[Dodgy69]

What's the general consensus on this.?

Modern 'sports touring' tyres are deemed pretty good for most conditions these days. Some probably better than others, going by reviews. So my question is, how much psi under manufacturer recommendation (book) do I reduce if any. ?

Does it vary on brand, weather, temperature or is it tyre specific. ? or

Does it depend on rider ability. Eg. Fast/novice ? or

Makes no difference on general trackday.?

Oulton park soon.

[weeksy]

Based upon the tyres you'll have, 30 30 cold will be close enough.

Some like the Racetec RRs are 24HOT for the rear and 32hot for the front, but you won't have them, so don't worry.

But anything road biased, somewhere round 30 for front and rear will see you right. Does it make a difference, i'd argue not much in Nov/Inter, but pyschologically maybe, so why not. MRs Weeksy runs Racetecs and warmers, i'm not convinced she really needs either and i could lower my tyre bill if she didn't... but it's what makes her happy and gives her confidence, which is all that matters.

[Dodgy69]

Book rec is F 33, R 36 cold. So reducing rear more.

[singlesman]

You’re really only interested in the optimum hot temperature, adjusting cold temp as necessary to achieve this.
If you could get a figure from the manufacturer for this that would help you a lot, probably quite a wide pressure range on a sports touring tyre compared to something race specific.
As you say in your opening post, so many variables, track temp, how hard you ride, make up of the particular tyre you’re using.
I’d be inclined to drop a couple of psi both ends work from there, too soft and you may end up with a evil handling bike on overheating tyres.
Cheers, Paul.

[Le_Fromage_Grande]

Run mine at 30 front and rear, tried fiddling round with them but couldn't really tell the difference, it's not as though I'm getting anywhere near the bikes cornering limits though, it's far quicker than me.

[Yorick]

When I was instructing, we always told punters to use 32 Front and 30 Rear.

But GPRacers were 20 PSI in rear.

[Tomcat]

I'm running Bridgestone S21. I asked Bridgestone Motorsport via Facebook for their recommendation, they said 32F/30R. Standard on the SV is 36F/42R.

The subject of track tyre pressures isn't simple and there isn't one set of pressures that works for everybody. At its simplest it's the flexing of the tyres that heats them up by hysteresis, not friction. Weaving does nothing. Friction doesn't start to come into play until you're on the edge of grip and the tyres actually start to move across the track surface sideways. What affects your grip is a mixture of temperature and pressure (which of course are linked). The tread compound needs to be hot enough to work but not so hot it starts tearing and balling up. The temperature also affects the running pressure of the tyres and hence the shape of the footprint for maximum contact area - too high a pressure and the contact patch shrinks, too low and it goes concave and also reduces.

So, you're constantly juggling a mixture of optimal temperature and pressure to give compound grip and contact patch, and they are linked because if your pressure is too low the tyre will heat more, increasing in pressure but with a higher tread temp. Unless you're running race slicks which only grip within a narrow temperature range you don't need tyre warmers, everybody's tyres will be at the same temperature within a lap or two. But it's generally considered that you reduce tyre pressures a bit to allow for higher running temperatures on track as you start to push things. The temps you use will depend on the tyres themselves, your and the bike's weight, and how hard you're going to push it. If you get recommendations from the manufacturer that's a good starting point and you can adjust after a few sessions according to what your tyres are looking like. Always adjust cold so you have a common baseline and remember tyres in the sun heat up and gain pressure.