AO48 pressure on track

Coming from a motorcycle club racing background, I’m struggling to get my head around the fact that you set the pressures hot as this is a complete no-no on a bike!?!?

Now you’re confusing me! Racing Bike tyres are kept in “tyre warmers” until the start of a race, just as Racing Cars’ are. Surely temperature & pressure are directly related

28 psi! I just can’t believe it.
But if it was, I assume it was hot, or there are other factors here that we don’t know.

But yes, different cars, setups, driving styles call for different pressures.


Bat, I used to race bikes as well, and have no problem on thinking in hot pressures either. But you want cold? they vary, but try 20-22 psi to start with.

28 psi! I just can’t believe it.

Oh yes, definately hot - have you seen Gav drive in a race? He drives a Lotus on track, like no one else I’ve seen - fair do’s, it is his job, but he has immense natural talent too

I think its clear that you cant just give advice like this without respect to the Geo and driving styles etc

I saw Steve tyres and yes they were getting scrubbed up a bit but then he is on LSS and I guess standard cambers etc. I would expect lower pressures to make the edges wear much quicker in that circumstance ??

Some scotish guys were at Zandvoort and they were advised to go really high 35 ?? and came back in and said how different it felt - far more grip etc

Personally I find 28 hot works just right, lower and it feels too loose. And I have -1 front, -2.5 rear and 400/475 springs with nitrons at the middle ( I know I know …) and full stiff ARB

But I’m going much slower than the rest …

You lot can never give a straight answer can you

whitty replies expected

There are so many opinions and, from past experience, we’ll just end up causing more confusion than help!

Ian

Never !!!

Are suuuuure?!

I saw Steve tyres and yes they were getting scrubbed up a bit but then he is on LSS and I guess standard cambers etc. I would expect lower pressures to make the edges wear much quicker in that circumstance ??

I’m on LSS too, -50" front camber, stock rear camber and run on from 17-19 psi cold to 20-22 psi cold, depending on the day.

But they I use a pyrometer and just adjust the pressure until the temps across are even…

I have full motorsport spec Geo on my car (track only) and Lotus Motorsport said to put the 48’s at 28 hot all around. I find this is a good starting point and I adjust as needed - usually a pound or two either way depending on the day.

Meat: share what your ARB & springs specs are!

Stock ARB and I believe my springs are 375/400 over Dynamics 2-ways. These springs are proving to be a bit soft so will be looking in the 600lb range this winter.

Why do you think that Rox? Surely you’re then not using all of the tyre (with the outside edge working harder)? Or am I just being impractical?

Randy (and others), your opinion would be of interest.

Ian

IDG

I don’t have a pyro, so haven’t measured this but I remember it being discussed a year ot so ago and i’m sure that’s what was said… it also makes sense to me because if you were running a lot of -ve camber (which most of us are) then no matter how hard you are trying, surely the inside and centre will be in contact more of the time than the outside ??

On the pressures thing… my car is bog standard and for mee feels much less grippy if the A048’s are too high prssure (I like somewhere in the 19-23 psi region with the rears about 2psi harder than the fronts… just my opinion and experience… so not definitive)

But the camber is there so when the car rolls in a corner more of the tire is in contact with the ground. On the straights (when less is) the force on the tyre is weight and drive (for the rear), let’s call it 250kgs per wheel. Hard cornering is going to give most of the load through the edges of just two tyre edges, perhaps 350kgs worth.

A poor example but I hope you get my drift.

Ian

A poor example but I hope you get my drift.

Surely drifiting would require an entirely different setup

At Bedford on the 5th it was pretty cold and with 24r-22f I could get the offside pair warmish but hardly any temp in the nearside (Anti clock circuit ) so then what do \I do?
Managed to spin on a right hand bend…“obvionsly” because the n/s tyres were cold therefor less grip.!
Well thats my excuse ANYWAY.

How about having different pressures side to side to allow for the clockwise circuits or vice versa, then ???

The procedure of setting the pressures warm will take care of that, as the side that is not working as much will not rise pressure like the other.

Therefore, if you set the pressures to all 24psi warm, next morning when you measure them cold you’ll probably find that the pressures are not even.

Clever system, eh?

The procedure of setting the pressures warm will take care of that, as the side that is not working as much will not rise pressure like the other.

Therefore, if you set the pressures to all 24psi warm, next morning when you measure them cold you’ll probably find that the pressures are not even.

Clever system, eh?

Cool response…








(Pun fully intended )

But the camber is there so when the car rolls in a corner more of the tire is in contact with the ground. On the straights (when less is) the force on the tyre is weight and drive (for the rear), let’s call it 250kgs per wheel. Hard cornering is going to give most of the load through the edges of just two tyre edges, perhaps 350kgs worth.

A poor example but I hope you get my drift.

Ian

wot u babblin on about boy ?