Tyre pressures
Discussion
Thought this deserved a thread of its own, really, as it kind of got buried in another thread.
What's the best technique for setting tyre pressures for this kind of event (i.e. mostly single laps rather than constant lapping)? Up a bit, down a bit, up a lot, set them to road pressures when cold and forget about them? etc.
Any good rules of thumb?
What's the best technique for setting tyre pressures for this kind of event (i.e. mostly single laps rather than constant lapping)? Up a bit, down a bit, up a lot, set them to road pressures when cold and forget about them? etc.
Any good rules of thumb?
It really depends,
We will definetly raise the tyre pressures, as high speeds create a lot of heat, and if there is less tyre contact with the airfield surface there will be less heat, and less chance of a blow out. Less rolling drag as well which means it should help with the old top speed.
However less grip.
This is my understanding, im sure someone with more info will chip in soon
all the best
adam
We will definetly raise the tyre pressures, as high speeds create a lot of heat, and if there is less tyre contact with the airfield surface there will be less heat, and less chance of a blow out. Less rolling drag as well which means it should help with the old top speed.
However less grip.
This is my understanding, im sure someone with more info will chip in soon
all the best
adam
On trackdays I lower the pressure in the CSL to about 26psi cold which relates to about 34 hot and the cups respond well. For Vmax I will keep them at the road recommendation of 36psi cold.
The Merc will be running about 41rear and 39 front and I reckon that will be fine. You can check the pressure and temp from the console in the Merc which is cool!
>> Edited by phatgixer on Wednesday 2nd March 12:46
The Merc will be running about 41rear and 39 front and I reckon that will be fine. You can check the pressure and temp from the console in the Merc which is cool!
>> Edited by phatgixer on Wednesday 2nd March 12:46
derestrictor said:
You can check the pressure and temp from the console in the Merc which is cool!
...whilst squishing pesky bugs!
Outta mah way von Der, I'm a commin' through...
Not so sure about that yellow peril though. Hopefully it will be like a nervous race horse and my helmet will make it flighty and refuse to start....
>> Edited by phatgixer on Wednesday 2nd March 13:00
phatgixer said:
phatgixer said:
You can check the pressure and temp from the console in the Merc which is cool!
...whilst squishing pesky bugs!
Outta mah way von Der, I'm a commin' through...
Not so sure about that yellow peril though. Hopefully it will be like a nervous race horse and my helmet will make it flighty and refuse to start....
>> Edited by phatgixer on Wednesday 2nd March 13:00
Thats what my neighbor calls the ctr..and shes 80!
derestrictor said:
See Daz.
First, the disclaimer! I have no technical authority or understanding of the mechanics/physics of this issue whatsoever.
I normally drop the pressures to 2 or 3 psi below normal cold temps. Do two or three laps, tyres heat up ----> pressure goes up and I drop them back to normal cold temps again, which with my car is 44 rear and 36 front.
DAZ
Pete. I've got a tyre pressure gauge thingamy which I'll have with me on the day if you want to borrow it.
>> Edited by dazren on Wednesday 2nd March 15:07
No worries Daz, I have a reasonably accurate guage in the car as a matter of course (its a bit sensitive to low pressures!)
Hmmm. Conflicting opinions here...
I must say that my initial thought was that dropping the pressures when the tyres had heated up would be a good idea but then I worried that (assuming a reasonable pause between laps) they'd be too low at the start of the next run.
I guess the only answers are to either leave them alone and hope for the best or experiment and see what feels best...
Hmmm. Conflicting opinions here... I must say that my initial thought was that dropping the pressures when the tyres had heated up would be a good idea but then I worried that (assuming a reasonable pause between laps) they'd be too low at the start of the next run.
I guess the only answers are to either leave them alone and hope for the best or experiment and see what feels best...
phatgixer said:
On trackdays I lower the pressure in the CSL to about 26psi cold which relates to about 34 hot and the cups respond well. For Vmax I will keep them at the road recommendation of 36psi cold.
>> Edited by phatgixer on Wednesday 2nd March 12:46
I thought for track and Vmax days you needed to up the PSI not reduce it ? Why are you lowering them on the Cups ?
Rick
ferrari355gtb said:
On trackdays I lower the pressure in the CSL to about 26psi cold which relates to about 34 hot and the cups respond well. For Vmax I will keep them at the road recommendation of 36psi cold.
>> Edited by phatgixer on Wednesday 2nd March 12:46
I thought for track and Vmax days you needed to up the PSI not reduce it ? Why are you lowering them on the Cups ?
Rick
They heat up better and give a larger and even spread contact patch at lower psi. The only reason to up the pressure is to stiffen the sidewall to prevent them rolling on to the edge. At really high speed the centrfugal force will try and keep the sidewall upright.
If you lower the pressure too much of course the rolling resistence will be high enough to cause massive heat build up in the tyre and could cause a catastrophic failure, so read the manufacturer recommendations about high speed running.
Gassing Station | Events & Meetings | Top of Page | What's New | My Stuff