Andy.F

Any suggestions for a decent trackday slick in 16" size ?

I recently bought a cheap secondhand set of Dunlop SP sport 16" slicks for trackday use, they are the type they use/used on the Vento challenge cars.
As they are a 'control' slick the compound is quite hard and even a hard 6 lap thrash just gets them luke warm I don't feel that they offer much more grip than my road legal Yoko 032R's

A similar car on a recent trackday had BF Goodrich slicks fitted, you could hardly put your hand on them and the owner was well pleased with the high grip levels.

Any recommendations welcome

thanks

Andy

Andy.F

Nobody giving any secrets away then

Pete Croney

Andy

Mess about with the pressures. Slicks are extremely pressure sensitive.

Too high and they overheat, too low and they never warm up. If they overheat, the wear rate is massive and the carcass can get damaged, delaminting off the canvas.

I run them high for a couple of leps and then reset all the pressures to around 28psi, hot.

The Yokies will have a good grip and you won't see a massive improvement, but a true slick should last longer.

Andy.F

Cheers Pete

I think I had them way too low My previous lightweight cars ran with 20 psi max and that's where I started !!

Will try higher pressures before I dismiss them as too hard or too old a compound.

thanks

Andy

Pavlo

I've always found you need to go either really high, or really low, and that there is always a bit in between where it's crap.

Very low pressures work well on very course tarmac, and put heat into the tyres due to all the tyre flex. Very smooth, fine grained tarmac seems to need higher pressures, which puts more heat in because more energy is put into the contact patch.

Ideally, if you are going round mainly right hand bends, measure the temps accross the tyres, the inside of the left tyres (trailing edge when sliding round right hand bend) should be about 3-5deg C higher than the outside, and about 2-3 deg higher than the middle.

Actuall pressures will depened on tyres, but harder tyres also seem to want higher pressures.

I used to use dry nitrogen gas in tyres to reduce the pressure change, but divers air is nearly as dry and cheaper. The water vapour in the air is what contributes the most to the pressure change with temperature.

Paul

DavidLewis

Helium can also resolve this problem and has the added benefit of reducing un-sprung weight since its lighter than air.

Andy.F

Yea, the alarm bells started ringing when my inside tyres were hotter than my outside (working) ones
I didn't take my tyre pyro with me as we were not even supposed to be timing laps let alone doing a race set-up routine

Will do next time though