ThePass

iTrader: (3)

Gigapunk - 36psi cold seems really high - unless the course was 30 seconds, that should rise to at least 39 hot... how much camber do you have in the front?

I think camber really matters a lot to determine how much pressure is needed, especially when just going by the outer wear marks (though I know you were using a pyrometer) less camber of course necessitates higher pressures to prevent roll-over.

At my last autox, on a BIG course (~100 sec), I started at 27 psi which heated up to ~32psi hot front and rear, and I was just grazing the wear arrows on the sidewall.

At Buttonwillow I ran 33 psi hot all around, and it felt really good. I need a pyrometer to determine any more useful info other than "it felt right"

GIGAPUNK

I usually run on courses that are around 50 seconds. And I usually only get a 1 psi gain, rarely 2. My front camber is maxed at 1.4, rear is somewhere around 2. I have a lot of trouble getting consistent information from the pyrometer on camber. The inside to outside temperature differential is very sensitive to the direction of the last couple turns.

ThePass

iTrader: (3)

You have very, very little front camber. I bet -2* camber would let you run 3 or 4 psi less in the tire... I'm at -2.2

GIGAPUNK

That's what I thought before I started testing. I even pre-ordered the next set of ISC racings front camber offset delrin bushings. Since canceled. But you'd think that if my camber was so far off that my outer shoulder would be getting significantly hotter than the inner shoulder. And it's not. Real racing tires like the A6, or even the R888 like a ton of camber some times even 5 degrees! But the RS3 is a street tire. A stoooopid sticky street tire. It seems it doesn't need the camber of the other tires per my pyrometer testing.

trakhoar

iTrader: (3)

With a 225 over a 9" wheel, you may not see much sidewall roll over to really use the side markers as a proper gauge.

GIGAPUNK

Also thought I should mention that the highest temp that I've seen was 137 F.

Nate99

Are you using a probe-type or infrared pyrometer?

GIGAPUNK

Harbor freight infrared. I put the thermometer against the tire immediately after the runs to improve accuracy. The infrared shoots out in a cone, so the farther you measure the wider the area you're measuring.

flier129

iTrader: (7)

I know I'm bringing back an old thread but... I had issues at a recent autox.

I normally run 30-33 front & 28-30 rear on a warm day. They usually squeal, as I'm sure most of you know that have autox'd some rs3's. Well last sunday they made NO noise... at all. Just massive understeer and even easier to lock-up. I ran the last heat of the day, but I did notice earlier in the day the lack of tire noise, unless they were locking up the tires or spinning out.

I'm hoping is was an extremely dirty/slick track and not my tires going out :(. I'll have to post up two different clips of me, one of the dirty/slick lot and another on a lot where my tires made actual noise.

Nate99

I'm going to guess the former. My RS3s are nearly at the wear bars (the outside tread grooves are nearly completely gone), and they were still making plenty of noise at the track today. This is on a track that's known for being pretty high wear (i.e. not slick).

Side note, how far have you all been running these down? I feel like mine have been noticeably slower at the last two track days I've run, but this could just be an excuse for crappy driving.

smbstyle

good thread, my RS3s are coming in tomorrow!

GAMO

iTrader: (1)

At CMP last weekend the car felt good at 39psi hot on all 4 corners on 15x7 wheels. -2 in the front, -1.8 in the rear.

smbstyle

what were your starting pressures?

ThePass

iTrader: (3)

Starting (cold) pressure is not important info because depending on the type of event you're doing, the track temp, and a bunch of other factors, each case will see a different amount of pressure increase. All that matters is hot pressure. For a baseline though, I'd say for an autox start ~3 psi below where you want to be, and for a warm track day start 4-5 psi low.

-Ryan