Tire graining Auto X

[330SMG]

1989 325i Bilstein IE sways.
I have pretty new Azena 615 with about 20 uns on them. They are working well but the front two are graining. We run on a concrete surface and it has been cool in the low 60's, ground temp is upper 70's. My surface temps are low hundreds for driver and only upper 90's on passenger. Running 32 up front and 27 in rear.

Any ideas? Too much pressure up front?

[GotCone?]

concrete w/ rough aggregate can grain tires.

post up pics of the effected areas and we can better diagnose.

[kilgojr]

What are your temps across the face of the tire? Outside shoulder, middle, inside shoulder? That would give you an idea of how your tires are reacting with the pressure. If your temps are high on the outside and inside shoulders and lower in the middle you need more air in the tire, if they are lower on the shoulders then the middle you need to let some air out. If they are higher on the inside and lower across the face to the outside shoulder you have too much camber.

You also need to take into account the layout of the course. I run in the Alabama region and many of our courses run in a counterclockwise configuration so my passenger side tires get much more heat in them than do the drivers side.

As for the tires themselves, I was very disappointed in the Azenis 615. I ran that tire last year during the beginning of the season in the 205/15 and then ran an autocross on my brothers set of Kumhos Ecsta XS in the 205/15 and it was like night and day. I'm not knocking the Azenis totally, its still a great tire for the price, but the compound is just too old. The newer ST group of tires from Bridgestone, Hankook, Kumho, and Dunlop are leaps and bounds ahead in performance. I personally think that Falken has focused more on the drift scene and left the Azenis 615 compound set up for the drift guys because it is a great tire to drift with, but goes away far too quickly for track or autocross.

[GotCone?]

my guess is that a pyrometer isn't in his tool box or this post wouldn't exist.

[nando]

$30 laser thermometer

not perfect, but cheap and decently effective

[JeffRR]

What are your temps across the face of the tire? Outside shoulder, middle, inside shoulder? That would give you an idea of how your tires are reacting with the pressure. If your temps are high on the outside and inside shoulders and lower in the middle you need more air in the tire, if they are lower on the shoulders then the middle you need to let some air out. If they are higher on the inside and lower across the face to the outside shoulder you have too much camber.

Just curious, but how much of a temp rise do you see after a Auto-x run?

Are you getting surface temps or do you see a change in the carcass temp?

[nando]

it really depends on the surface, the tire, the ambient temp, the driver and the car..

but generally, I'd say a 50f rise isn't out of the ordinary.

[330SMG]

my guess is that a pyrometer isn't in his tool box or this post wouldn't exist.

I have an infrared Therm just did not think to post
the best surface temps I got were
120 outside 115 110 on Driver
100 outside 95 90 on pass
The course had a tight left hand turn around and a hard left than right at the end.
I was really thinking about this after I posted and i looked at my notes and I need two pounds of air in the fronts.
My front sway 25mm is full stiff and my rear 22 mm is close to full loose.
I am stuck with the Azenas since I am running bottle caps for cheapness and weight. They are good as long as the surface temp stays below 140-150, after that they are grease.

They are changing the compound that is why you get $80 of a set now.

[nando]

sounds like your pressures are ok, but you need more negative camber.

[330SMG]

sounds like your pressures are ok, but you need more negative camber.

I have -1.8 degrees. This is a street car.
This was the first time in 3 seasons I had graining. May be the conditions where perfect for sucky tire wear, low 60' dim sun and lots of wind.
Next one is in May should be a lot warmerand that will probably resolve issue.

[jlevie]

Those tire temps strongly suggest that you don't have enough camber. I'd suggest trying 2.5deg. If you set the toe to zero tire wear on the street shouldn't bee too bad.

[2002maniac]

You have run azenis on this surface in the past without graining? You do need more camber, but that wouldnt help the graining much. I suspect it's just the surface conditions of the course.

[Skafrog]

not enough camber, and welcome to going fast.