Tire Pressure for Track Day's

[ashbox]

The Dragons I have had for around 18 months now, got them for $215 each. The car has had a MAFLESS tune and cold air induction (OTR). Got about 90 extra KW's out of her - she's now pushing 221KW@164KPH (on the Dyno).

bit off topic but what was the car running before the tune and otr....
90kw gain and to only be putting out 221kw..?

 

[CRUSTIN]

Maybe he meant RWKW? But i doubt a tune+OTR would do that.

 

[crazybiker]

I'd probably start on about 27-28, depending on how well the car hooks up as it is.

If the tyres really bite into the road, they'll generate more heat through sidewall flex, so you need to minimise the amount of flex, and therefore heat generated, but keeping pressures right.


When you think about it, you can go quite low, depending how hard you push. Obviously you won't be going as hard as the V8 Supercars, but they run starting pressures of around 18psi

 

[old mate]

i still cant find that article, its driving me insane. i should have a few hrs tomorrow to look for it though.

in reference to the v8 comment, alot of slick race tyres need lower pressures to be in their ideal operating temperature range. i know that with my racebike i need to run around a 25psi area when the tyre is on the warmers, so thats around a 20 - 22psi cold range. but if you were to run a street tyre at that pressure, you would likely tear it to bits.

 

[Darcon666]

I run Bridgestone RE55S 245/40/18's (http://www.bridgestone.com.au/tyres/motorsport/RE55s.aspx) @ 28psi and at the end of a three lap super sprint they are @ between 38-40psi(This is @ Wakefield Raceway)but I like them firmer @ that track.... others prefer them softer so they aim at 24-26psi cold starting pressure --> and end up @ between 34-36psi. Eastern Creek on the other hand is completely different kettle of fish, I start them at 24psi and end up @ 38psi as the track is more abrasive and generates more heat into the tyres and so ends up being higher.

As stated by others... I would start them @ 30psi, do 3 or 4 laps come in check... anything above 40psi is too much for the circuit you are on. Drop them by 2psi and go again for another 3 or 4 laps and see how they feel then come in and check, continue this until the car starts to NOT feel comfortable.

Alternatively, find a store that has nitrogen and empty all the air out and fill... as nitrogen does not expand when hot. So you start @ 38 cold and you end up @ 38 hot but the tyres in my books feel strange, but that's just me.

Just my 2c... *lol*

 

[TI3VOM]

The Dragons I have had for around 18 months now, got them for $215 each. The car has had a MAFLESS tune and cold air induction (OTR). Got about 90 extra KW's out of her - she's now pushing 221KW@164KPH (on the Dyno).

Very nice power your making there mate, it would be fun to drive!

One thing though, when the tires are worn upgrade to some better rubber for the track days, at the moment mines running Pirelli PZERO NERO's that I picked up for $208ea that's for 17" wheels mind you, they perform very well.

Do you have anything done to the suspension?

 

[craigsmonaro]

OK so this is what I think I will run with (track day is tomorrow). Start with (cold tires) 45 front and 42 rear, do about 3-4 laps to warm up, then bring down the pressure so they run at 43 front and 40 rear (hot). Obviously see how it goes and adjust slightly, but I am thinking higher rather than lower. Given I am running at Wakefield it is predominantly a right hand track so the pressure in the right hand tires will be different to the left, so the idea is to even them out so even pressure across each side. My only concern is that 43/40 may be too high…

For those that were wondering, I have attached my Dyno stats of before and after the tune to give you an idea what I have got. Can’t wait – will be a fun day.

 

[ashbox]

sorry but wtf.....
132.4kw before tune and 153nm torque?

if you re-read darcons post, he recommends 28 psi cold for wakefield top be at around 38 -40 hot

 

[old mate]

best of luck but 42f 45r cold pressure is too much.

 

[craigsmonaro]

Well, track day's been and gone, and yes it was a brilliant day! Track time in the Monaro was 1min19 - pretty happy with it! Got a few ideas of what to do with the car next, but I will start a new post on that one.

Anyway back to tire pressure, I was a bit optimistic in my last post - I started the day with 38 cold in all tires, and found I was constantly letting the air down during the morning - Settled with 42psi hot in all tires. Car felt nice and gripped well, wasn't squeaking and tire wear was even. I kept the pressure a bit higher based on some 'professional recommendations' from some of the guys at the track. I can't comment on if it would have been any better with lower psi (eg 38 as Old Mate recommended) but I was really happy with how the car went, well apart from the brakes but that's a whole other topic…

Thanks everyone for your advise - it defiantly helped.