71 replies to this topic

[Gedi]

*edit, sorry wrong thread

Edited by Gedi, 03 November 2014 - 09:16 PM.

[chris_uk]

Recommended hot pressures for 888s and ZZRs are 28-30 psi and is covered on their web sites. Both advise against going into the low to mid 20s Can't comment on other tyres

 

is this for a lotus type car then? because you run them pressures on a 2 tonne car and the temp outcome is going to be very different to that of a vx220 at 30psi. 

 

if its this..... 

 

http://www.avonmotor...performance/zzr

 

your referring to is this "on track" pressures?.. it also seems to be pointing towards the lighter weight cars which is good because our cars fall into the same category.. so at 30 psi on a moderate day (when the tyre is working at its best) you need to take a measurement of the temps across the tyre and use that result as a target temp so regardless of weather condition you always know the tyre is working optimally. 

Edited by chris_uk, 03 November 2014 - 09:27 PM.

[techieboy]

 

Recommended hot pressures for 888s and ZZRs are 28-30 psi and is covered on their web sites. Both advise against going into the low to mid 20s Can't comment on other tyres

 

is this for a lotus type car then?

 

See Max's post at the top of this very forum.

[PaulCP]

 

Recommended hot pressures for 888s and ZZRs are 28-30 psi and is covered on their web sites. Both advise against going into the low to mid 20s Can't comment on other tyres

  is this for a lotus type car then?

  See Max's post at the top of this very forum.

In addition to the post which Techie refers to, which relates to Lotus/VX type cars, you need to remember that the ZZRs were made specifically for the LOT race series So yes, those pressures are for Lotus/VX type cars on track But if a different set up feels better to you then there's nothing wrong with gut feel at our level of competence.

Edited by PaulCP, 03 November 2014 - 09:47 PM.

[siztenboots]

re: aquaplaning you get a bow wave forming in front of the tyre. at some point the rate of removal of fluid is too slow, then the tyre rides up the bow wave becoming a water wheel. the rear tyre should follow in the trough cut by the front tyre. you could add an infinite amount of front downforce for no effect, water is incompressible ( bulk modulus of 2,200,000,000 )

[manus]

Recommended hot pressures for 888s and ZZRs are 28-30 psi and is covered on their web sites. Both advise against going into the low to mid 20s Can't comment on other tyres

But suppose it depends also on the weight of the car. VX's are less than average and to achieve balance inside the tire and outside you should probably adjust? The rubber should be pressed evenly to the tarmac from centre to edge for best grip. Suppose if you increase pressure in the wet the tire will expand like a balloon an would be capable of moving more water to the side. And the reduced contact would increase the weight per square inch, also helpful. On the downside it will wear in the middle. Same as running 30 psi on a VX..... .... should be 24. Try it.

Edited by manus, 04 November 2014 - 04:20 PM.

[PaulCP]

............. Read on, catch up😎

Edited by PaulCP, 04 November 2014 - 05:32 PM.

[manus]

............. Read on, catch upøŸ˜Ž

The table mentions " measured at" and not "recommended to run at ... PSI". Or should I read further back? I'll start reading.... http://exploratorium...ight/index.html

Edited by manus, 04 November 2014 - 06:22 PM.

[PaulCP]

Interesting point on running lower than 22psi cold http://www.avonmotor.../lotus-on-track http://www.vx220.org...tyre-pressures/ All VX/ Lotus related, no doubt a certain level of "safety" tolerance built in but who am I to question their views😛 Anyhow, we're off topic now, dry track pressures have been done to death over the years As I mentioned before, whatever feels good is right (within safety limits), at our level. We wouldn't be posting on here if we were any good😄😄

Edited by PaulCP, 04 November 2014 - 06:50 PM.

[cnrandall]

For racing I run as little as 16psi cold on a ZZR and on the 48's I would sometimes end up lower than that.  With tyre pressures you need to aim at the right hot pressure and the cold pressure will end up where it ends up.  Obviously track day use isn't going to put as much heat into the tyre so correspondingly higher pressure cold is required.

 

Wet setup leave the dampers alone if they are single way, maybe try 2 clicks softer but if they are set correctly from the outset then dropping them off will loose control of the spring.  Best changes to make in the wet are less camber and softer springs but your spring are already soft.

[chris_uk]

not talking about wet temps here but why does everyone barter on about the best cold starting temps?? .

 

go out  with normal road pressures and do 4 steady laps, come in and alter your pressures until they all read 30psi 

go back out and do another 4 laps, this time a bit faster, then come back in and alter your pressures until your back down to 30psi. 

go back out for a final time at a pace your comfortuble with and then after 4 laps go back to the pits make it 30psi for the last time..

 

once you have done that.. leave it alone until lunch time.. when lunch has finished go out do a session come in and the tyres (depending on how much the ambient temp has changed) should still be pretty much around 30psi.. thats what i do anyway. 

 

psi shouldn't be used to measure a tyres optimal performance as i keep saying, it should be temps but since its easier to measure the psi thats what people go on about.. ideally you want a target temp across the tyre and they use a temp gauge to measure it.. then once you are at your optimum temp take a reading of the psi.. then once you have that number you when your running that psi hot you know your almost in the ball park figure.. obviously weather conditions etc will mean that pressure needs to be increased or decreased to find that optimum temp again.

Edited by chris_uk, 04 November 2014 - 08:13 PM.

[cnrandall]

30psi is a bit much for most tyres on these cars... more like 27/28 and a psi lower on the front than the rear.

[PaulCP]

@Chris_uk. - Agreed, that's what I do and yes psi is measured since its the only one available without investing in other equipment, and using 888s and ZZRs I usually aim for 28 front & max 30 rear.

Edited by PaulCP, 04 November 2014 - 08:55 PM.

[mbes2]

After all this bet friday is super dry & sunny 

[Acidpopstar]

After all this bet friday is super dry & sunny 

Which track day you doing?

[Andy_VX]

Lol its certainly stirred up a lot of discussion! It's still forecast to p*ss down all day so pretty annoyed! It's just an airfield day at Hullavington.

[Andy_VX]

Well, the car was absolutely incredible on track! I was very apprehensive about how it would handle in the rain but it was awesome. So much grip even in low gears. The only thing letting it down were the brakes, they were ocerheating after about 5 laps and giving me a long pedal. I have Mintex 1155 pads, 5.1 fluid and braided pipes so I think it's just a cooling issue or maybe moisture in the fluid. Unfortunately we had to pack up early, my dad had a drive and was pushing on harder than I was, then all of a sudden we lost all power. We limped back to the pit and read the fault codes. The engine was in a safe mode. I let it stand for a while and it was fine but we noticed the pipe going from the cc to the intake manifold was collapsing under revs. I thought that was a bit odd considering that air is being pushed through it not sacked. Hopefully it's just pipe getting too hot and I can upgrade to the Courtney one. (already have the Courteney intake pipe) Still really happy with the VX though, it's performance way outshines my talent. It was quicker than everything on track apart from a very well driven e36 M3.

Edited by Andy_VX, 07 November 2014 - 02:45 PM.

[mbes2]

What about the tyres, did you change any setting or just drive as is Track days are good fun

[Andy_VX]

It felt pretty good from the initial settings to be honest so didn't alter tyre pressures in the end. Theyvere very sticky after a stint though which is good. Loads of standing water so theyvere never really hot. Was going to have a play with suspension and pressures after lunch butte pipe stopped that!

[Acidpopstar]

What tyres you running Andy? Scrolled through 3 pages and can't see a mention. Glad you had a good day. Croft was underwater most of today.