Looking for advice on tyre setup for use on tracks.

[Bob and Carol]

​​​The pictures are taken after a track day at Anglesey last Monday.

Near Side Front

Near side Rear

Off Side Front

Off Side Rear

I started the day by dropping from 21PSI to 18PSI

A gentleman said he runs his at 29PSI but said it depends on the tyre you are using, and recommended I looked at the surface temperature as soon as I came in and change the PSI until the outside edge matched the middle of the tyre. Higher middle temp, drop by 2 PSI, lower middle temp, increase by 2PSI.

As this sounded a reasonable way to balance the temperature across the tyre and this would allow for front to back tyre pressures to differ and nearside to offside for a right handed circuit, I gave it a go. When I got back home the pressures were 15PSI near side front and 16PSI for the other three.

Knowing very little about track driving and setup, please could anyone give me some pointers to changes on what I could do before my next trackday, which will be at Croft.

I have included a picture of each tyre as I was puzzled by the rubber deposits on the nearside compared to the offside tyres, all may be normal, as I said I know very little so any help please.

Caterham 420R with Avon185/55R13 ZZR front and Avon 215/55R13 ZZR rear.

Half tank of fuel and driver, corner weights are within 1%.

Front camber 2.25 deg.

[anthonym]

Have you got a pyrometer? For the purpose not one of those infra red ones.

I use this type, though mine is now a bit long in the tooth but my use case is high altitude alpine not track

https://www.longacreracing.com/products.aspx?itemid=1721&prodid=7295&pagetitle=Standard-Memory-Tire-Pyrometer

This one looks tasty for racing etc

https://www.longacreracing.com/products.aspx?itemid=1721&prodid=7293&pagetitle=Deluxe+Memory+Tire+

I imagine racers will be along momentarily

This looks relevant to your question

https://www.longacreracing.com/tech-central.aspx?item=46317&article=Tire%20Temps%20Tell%20a%20Story

and the notes to this item are very specific

https://www.longacreracing.com/products.aspx?itemid=7339&prodid=7339&pagetitle=Temperature-Compensated-Digital-Tire-Pressure-Gauge-0-100-psi

Anthony 

[Nigel Blandin]

Here is a good Avon tyres guide for you to peruse, 

Club tyre pub

[mph]

*Looks up pyrometers, goes down new rabbit hole*

[graearea]

from what I understand it's 22psi (for 15" ZZS/ZZR) whether they're hot or not.

if they get hot the pressure will go up, overinflating them which means a high middle and less grip. go out, do some laps, check the pressure when you come back in, drop pressures appropriately

all the rubber in the middle would make sense if you're massively underinflating your tyre (which 15psi is)

 

 

[Bob and Carol]

Thanks Anthony, Nigel and graearea.

I altered the pressures to make the centre match the outside edge of the tyre but did see a large difference to the inside edge temperature.

Looks like camber is the first way to go and more air in the offside tyres to stop the rubber build-up.

Would I be right in thinking different cambers on EACH wheel would help to balance the temperatures?

Thanks for the links, interesting reading.

[SamC]

The desired camber is more related to your spring rates and geom than temperature control.

Effectively, with camber, you just want to be creating as large a contact patch as possible in the 'average' corner. That doesn't differ from left to right on most tracks (not always the case, but certainly a level of complication I'd suggest isn't worthy of concern unless absolutely on the limit).

Obviously too great a camber value will harm traction and overheat/wear the inside shoulder, so it's a balancing act.

Once you find a value that works for you, I wouldn't imagine you wanting to change it greatly from circuit to circuit, and will more than likely keep the same across axle. As with everything though, there is a huge dollop of personal preference in the mix too, so within reason there are no real wrong solutions!

Unfortunately I don't have much experience with what tyre pressure values to run, but I'd definitely suggest a pyrometer (doesn't need to be expensive, just consistent and one that can measure at about 2mm depth), and I'd also only measure my pressures immediately after a run (they will then correspond to the ones Avon refer to in the PowerPoint). Once everything is set as you like, take a reference read when everything is stone cold (just before the first run after lunch/the morning after the track day etc) and use that as your starting pressures next time. 
 

Hope that helps!

[Bob and Carol]

Absolutely, thanks SamC.

[aerobod - near CYYC]

With Anglesey being a clockwise circuit with more right hand turns than left, hotter near side tyres are likely. If you mainly use that track and start to experience uneven tyre wear, it might be worth swapping the tyres left to right halfway through their life as they are directional, although the wear pattern may be set such that the grip may be a bit less until they wear in again on the opposite edge.

[Bob and Carol]

Now that’s a good reason to tell Carol I need to buy myself tyre machine.

[ScottR400D]

When we first tracked my car we were running about -1.75 deg camber. The outer edge of the ZZRs wore very heavily over 1 day. 

Having a tyre changing machine (!) I swapped them round as James has suggested. 

Subsequently we've always run 2.75 deg and find the tyres wear and heat quite evenly. We run at 18psi ambient. 

 

 

[aerobod - near CYYC]

Although I'm running the AR-1s vs ZZR, the compound characteristics and grip levels are comparable, I also have found the same as Peter (Scott) that more camber has been beneficial to more even tyre wear for track use, with -3.0deg on the front and -2.7deg on the rear. This level of camber may be problematic for predominantly road use, though.

[ScottR400D]

That's what I've found. 2.75 on the road, coupled with the tie out we also run on track, makes the car very twitchy and unpredictable on our roads. 

Bumps, road camber and grooves and tracks from trucks etc have it all over the place. 

Dropping back to 1.75, or a touch less, and removing the toe out settles it down. 

[Bob and Carol]

Thanks for all the info chaps. I now have a better idea where I have been going wrong.

Using a hand held infra-red temperate display.

Checking the temperate after I have done a cool down lap.

So the changes I plan to make are:-

1/ Come in after a hot lap and take readings of each tyre as quickly as possible.

2/ 0.75 Deg more camber on the front.

3/ Start the day with more air in the tyres.

Looking to replace the infra-red temperature gismo, what do you think of the following:-

https://ratemperaturesensors.co.uk/budget-racing-tyre-temperature-probe-kit-with-choice-of-probes-2231-p.asp

with the Fixed Tyre Probe (1 to 6mm) or the Adjustable Tyre Probe (1 to 15mm)

Having read the help from you all I thought it best to check with you on the above and please to add to the list, if you would be so kind.

[Bob and Carol]

Just a thought, as I will have to reset the toe after the camber, any recommendations?

For track driving only.

The toe out is 50’at the moment, as it came from Caterham.

[aerobod - near CYYC]

50' sounds reasonable for toe out track alignment. My car currently has 37' toe out on the front and with custom rear deDion wedges, 32' toe out on the rear, giving me a balanced amount of good turn-in without too much straight line dartiness.

[ScottR400D]

Bob, increasing the camber will increase the toe out slightly so I'd check it after adjusting the camber. 

Also, if you can , make a note of how many turns of the top joint and steering links you make so it will be easier to get back you your road setting. 

From memory 1 turn of the top ball joint is 0.25deg so you need to increase by 3 turns. 

[Bob and Carol]

Thanks ScottR400, that's exactly what I found I needed to do, three turns in.

What do you think of the link in my 09:55 posting of this morning?

[ScottR400D]

Looks OK to me Bob. I would think it's as accurate as anything in a reasonable price range and anyway, as long as it's consistent it will do what you want. I would think the way you use it will be just as important, push the probe in to the tyre the same distance, leave it there for the same length of time etc.

Any other Track Days planned? Let me know if you're going to Snet any time.

Peter

PS, meant to say when we spoke, do you have a splitting tool for the top joint? Obviously you do! One here if not, for next time.

[Bob and Carol]

Thanks Peter (ScottR400) I will get one on order. Thruxton skid pan this Sunday but with ZZS RT7 tyres then back to the ZZR tyres if dry for Croft on the 26^th and see what the tyres look like and if the under steer is any better.

I decided to go with James (aerobod) settings of -3.0deg front and set the toe out at 45’ to closer match his set-up.

At the moment I am happy with the rear so just noted the setup as it came from Caterham -1.75 camber and 12’ toe in.

[ScottR400D]

Keep in touch Bob! I'll see you when we can both make a meeting! 

 

 

[DW199]

Has anybody used a real time tyre temperature monitoring and logging system such as the Racelogic?  If so, was it useful?