HPDE experiments, results and observations

[rhyary]

Originally Posted by MaX PL

close enough?

https://rennlist.com/forums/racing-a...-for-free.html

Thx.
I found one on Amazon.
Lousy price, but together with the one I got from TR for $155 it averaged out ok.

[rhyary]

One day on MPSS at NYST.
luckily I did not pay full price but still.

this is on 1:38 pace with one lap 1:37.8

[rhyary]

Very happy with the 305/30/19 V720 on the rear.
Everything I wanted from a 200tw rear tire.

While there is tread left, I can see a small chunks coming off next to the wear bar and there is no need to push more. Heat cycles wise they are done as well.
.

[///Mobbin]

Originally Posted by rhyary

One day on MPSS at NYST.
luckily I did not pay full price but still.

this is on 1:38 pace with one lap 1:37.8

I've chunked MPSS in a day before as well, just weren't made for it.

PS4S on the other hand -- excellent do-it-all tire! A few seconds slower in pace than the 200tw favorites but really fun tire regardless. They do get greasy after a warmup and a few hot laps but they don't seem to chunk like PSS did (this over many track days for me).

[rhyary]

Originally Posted by ///Mobbin

I've chunked MPSS in a day before as well, just weren't made for it.

PS4S on the other hand -- excellent do-it-all tire! A few seconds slower in pace than the 200tw favorites but really fun tire regardless. They do get greasy after a warmup and a few hot laps but they don't seem to chunk like PSS did (this over many track days for me).

I did the same thing to a PS4S at NYSt
and.. The MPSS was great at LRP, perhaps not as fast a RT660 or RE-71R but nevertheless satisfying fast and predictable.


Here is the last session from yesterday for your entertainment.

You can see me working to find front grip.

few laps on 1:38, cool down lap and 1:37.87
The last lap on 1:37 is on the passenger tire pictured above :-(

[///Mobbin]

Originally Posted by rhyary

I did the same thing to a PS4S at NYSt
and.. The MPSS was great at LRP, perhaps not as fast a RT660 or RE-71R but nevertheless satisfying fast and predictable.

Interesting on the PS4S, I should note that I was running some beefy sizes, 255/40r18 fronts and 285/35r18 rears -- perhaps the amount of rubber helped dissipate the heat. I also didn't push them too hard after they got greasy, would let them cool then go back out.

[slcook54]

This is square 275/35 PS4S after 7 days. Consistently greasy after 3 to 4 laps. Never cooled them off in session, just kept driving on them for the full session.

[rhyary]

Watkins Glen Turn 1
SYT_Shadow "makes me" go wider on Turn 1
.

[rhyary]

Watkins Glen T-1 wide.

So I did :-)

[DoubleYellow]

Originally Posted by rhyary

Personal Best at PMP 1:48.08

Tires:
Front 265/35/19 RE-71R just before cords
Rear 305/30/19 V720 getting old but not on the wear bar yet

Weather was good.
Unfortunately, while I had space, almost any lap I ran into someone eventually.
Many laps on 1:50, 1:49, and two laps on 1:48.

Two clear laps on 1:48.x
First one is second session
Second lap is last session

Second lap in the video is my PB

Good to get an e92 M3 reference for Palmer. Enjoyed riding along. Supercharged S65 is a different ball game - so much more torque. I'm on stock power, MT, NT01, MCS2WNR, no aero, with 1:51.81 PB and 1:49.53 optimal. More seat time coming this year to boost consistency.

You should try running with these fast guys: https://www.comscc.org/events/results/view/?id=2022-02

[rhyary]

I won HPDE session!

.

[dparm]

So this thread is now 26 pages...is there a summary of findings to date? A table with some data for people to reference?

The thread started as a tracker for the 2020 season and we're now in the summer of 2022. Curious to find out what the community can learn from ~2.5 years of tire testing.

[rhyary]

Originally Posted by dparm

So this thread is now 26 pages...is there a summary of findings to date? A table with some data for people to reference?

@dparm,
Can you point me to an example of what you are looking for?

[sbo76]

:bookmark:

[rhyary]

Quick update and no video.
Was at NYST on Monday in beautiful weather.
295/30/19 MPSS Rear
285/30/19 RE-050A on the front.

Not much to say on the rear.
Front was interesting. The RE-050A had the normal road tire understeer, but it is a tough cookie. unlike the MPSS, it did not disintegrate.

Times were not fast. 1:40 mostly. This required me to use all the tricks I know to get down to 1:38. So it was educational but not fast.

Today I am with the same setup at LRP.

[rhyary]

LRP on 285/30/19 RE-050A and 295/30/19 MPSS.

Car felt good and balanced. But not fast.
Only manage 62sec laps with significant understeering.

If I was inclined to be more aggressive, I probably could have gotten down to 61sec laps but at the cost of overheating the tires and increase risk and I saw no point in forcing the issue.

I have tried many sizes and tires on the front. There is something about the 285/30 size that makes the car glide vs bite. Not sure how else to describe it.

Perhaps 285 does not work well on 9.5" rim.
Perhaps the side wall is too short
Perhaps the kind of rubber used in that size is not meant to be on track.

Regardless, I am giving up on that size.

Sizes I have tried on the front and gave up are:
245/35/19 OEM
255/35/19 nice but not better than 265
265/30/19 (way too short side wall)
265/35/19 (so far feels the best)
275/30/19 (side wall to short but fast on RT-660)
285/30/19 (something about this size is not working for fast trackday, feels great on the street. Feels very sporty and nicely protect expensive 9.5" rims)

There is only one thing about the 265/35.
For the rear I have three sizes I like:
275/35/19
295/30/19
305/30/19

The one thing I don't like is when the front diameter is larger than the rear such in the case of 265/35 front and 295/30/19 rear.

I have quite a few 295/30/19 tires in inventory that will have to be paired with the 265/35 front. My fastest LRP day with multiple 60sec laps were on this "unfavorable" combination. That day I was on 295/30/19 RR and 265/35/19 RT-660 and I felt like I can push that car to go as fast as my skill will let me.

[tsk94]

285 just too wide for a 9.5" wheel.. No sidewall support.

What don't you like with the rear diameter being smaller than the front?

[rhyary]

Originally Posted by tsk94

285 just too wide for a 9.5" wheel.. No sidewall support.

What don't you like with the rear diameter being smaller than the front?

A 9.5" is still within spec of 285mm but yes, less sideway support.

Mainly for the rake reason.
you can adjust the hight, but I don't want to mess with spring adjuster or with the alignment.

Ideally you will adjust the suspension for every variable but it is just not practical for me.

[rhyary]

I just compared my early spring 61sec lap at LRP with V720 305/30/19 and RE-71R 265/35/19 with NO supercharger to yesterday lap mentioned 295 / 285 setup.

While yesterday straight speeds where significantly faster, the total lap time was a sec slower.

61sec lap no supercharger (intake lifted)
coming into T1 122mph
into T5 103mph
downhill 97mph

62sec lap yesterday
Into T1 133mph
into T5 112mph
downhill 102mph

It is also a good indication how a light E46 on Hoosiers with a lot less speed than a supercharged E92 is difficult to keep up with, but I try anyway.

[tsk94]

Originally Posted by rhyary

A 9.5" is still within spec of 285mm but yes, less sideway support.

Mainly for the rake reason.
you can adjust the hight, but I don't want to mess with spring adjuster or with the alignment.

Ideally you will adjust the suspension for every variable but it is just not practical for me.

Ya that's the downside (one of..) to varying tires and tire sizes so often, rake always changing.

I realise the 285 is still within spec to physically fit on a 9.5", it's just far from ideal.

[rhyary]

Few laps on 62 seconds at LRP with SCDA.

[rhyary]

LRP T-3 throttle oversteer oops.
And.. you would think driving in the instructor group you will get a timely point-by.