Tire pressure for Trackday (G4/4)

[sydh70]

Hello,

Next sunday will be my first trackday, and it will be with my G4/4.
I wonder the tire pressure I should obtain when hot ? And what could be the cold pressure corresponding ?

Tahnk you for advices.

Sylvain

[GinG15]

first of all we need to know what tyre size you have fitted.

low profile ones for example need less pressure.

[GinELla]

If you run street tires, inflate to the max recommended when cold, never mind hot pressure. You find the number on the tire wall.

[GinG15]

i think that the pressure you recommend will negatively effect the road behaviour of the car...especially on such a kitcar without much weight on the back axle.

also depends how long the car will be constantly driven during this track day.

1 or 2 laps, afterwards a short break, than another 2 or 3 laps...also depending on the length of the circuit.

[mikeg15]

My friends use ACB10s , I have Kumho V70s - both on 6 and 8" rims. Both seem to like a temp of 22psi when hot. Depending on the ambient this usually means setting at 16 - 18psi when cold. Measure the temps immediatly after your first run while tyres are hot and adjust accordingly.

[sydh70]

The lenght of the track is 3.5km.
Tire size : 185/60/R13. Street tires.

20 minutes for each "race".

Thank you.

[GinG15]

i would say 1,4bar should be ok.

sorry folks, we have to speak about "bar" not "psi" as the question was aksed from somebody outside uk...and nowhere else in europe, besides UK , PSI is used!!

[sydh70]

And sorry, I have to speak in Miles and not Kilometers

[jamesG20V6]

It depends on your wheel construction also. Are they rolled edge wheels? (stops the tyres coming off at low pressures) Also pressure is pressure not volume so low profile tyres etc should make no difference.

[GinELla]

GinG15 said:

i think that the pressure you recommend will negatively effect the road behaviour of the car...especially on such a kitcar without much weight on the back axle.

OK, I stand corrected. Seemed to work for my '56 Corvette and '73 G15, both on radial street tires. But this was during much shorter duration than 20 minutes.

Even with max recommended pressure cornering like this left scuff marks on the tires' white wall.

Edited by GinELla on Tuesday 9th March 17:30

[jamesG20V6]

^ I think that might be down to the suspension design. Inflating tyres to the max rated pressure of the tyre for motorport is suicidal.