Optimum trackday pressures for 14" tires

[Panici]

I'm running a set of Kumho Solus KR21 - P195/65R14 on my 14" iS basketweaves

I know a 65 aspect ratio is not ideal, as there will be a lot of sidewall flex/roll.

Any suggestions for tire pressures? Tire wear is not a concern.

Obviously the issue is balancing lower pressure for maximum contact patch and higher pressure to prevent the sidewalls rolling over.


For reference, the Max Sidewall pressure is 44psi, and I normally run 35psi on the street.
Also, I've got some mild ride height lowering front and rear, so that has added some negative camber, which should help.

[redlightpete]

You might just start with your street pressure cold and see how the outside edges look after the first session. The hot front pressures will probably need to be well over 40 to get somewhat even wear in the front.

[Panici]

You might just start with your street pressure cold and see how the outside edges look after the first session. The hot front pressures will probably need to be well over 40 to get somewhat even wear in the front.

Roger that.

I'll report back so we have some data.

Cheers!

[Panici]

Reporting back with some data, as promised!

Started the day off with tires at my street pressure (cold 33.5F, 35R).

Front tires after the first (~8 minute) shakedown session.
Unfortunately I didn't get a look at them after my 4th session, where I ran my quickest (pre-rain) laps.





Then we got some rain, and I swapped ends a few times before I pitted and dropped tire pressures to (Hot 30F, 30R), which seemed to help.

I didn't mess with pressures any further that evening, although looking at my tires afterwards, the fronts could have used some more pressure as the track dried up and I went quicker.

I'm hoping to get back for one more evening session before I put the car away for the winter. I'm going to start at (33.5psi cold front and rear) this time, (hoping for some more rear end grip) and keep and eye on the tires to see if I can tweak the pressures further.


Front tires afterwards (took pictures days later, it rained for a while!)


Rear tires afterwards


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Oh, and a video of my aforementioned quickest lap
(There's a link in the description to the full 4th session video, if you're interested)
https://www.youtube.com/watch?v=K_kMTAj2gZk

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[redlightpete]

You could be pushing those a lot harder. That's about what my tires look like after commuting to work. It's not like a motorcycle where your track day is over if you lose the front end once.

[Panici]

You could be pushing those a lot harder. That's about what my tires look like after commuting to work. It's not like a motorcycle where your track day is over if you lose the front end once.

I'm aware.
It was my first ever trackday (well evening, it was a 4pm-dusk event) in a car, and the first time I've driven my E30 at that level.