Tire Degradation & Data

[GSpeed]

Originally Posted by glamcem

I understand but still doesn't give us enough information since there are many other factors (engine power, pad/rotor life, etc) that affect the lap times and tires alone cannot be held responsible for the overall lap times, especially when they don't heat cycle out and when the tests haven't been done consecutively



yes, take a look at this video, and listen closely after 3:38 mark





Jake I understand your points and agree with most of the things you mentioned here but I have to repeat; that sudden jump on IR temp readings for that specific corner where you see higher corner speed also backs my claim.. it looks like that relationship is pretty obvious, I am not judging the inaccuracy/accuracy of the sensors I am just comparing data horizontally



it looks like RE71Rs are great tires along with the Direzza ZII and RS3s many people so I agree with you on that

, I was under the impression that you were not satisfied with the results hence the word "degradation" and since you said: " Blue session should have been noticeably faster than the other two sessionsWe simply were not developing the lateral load that we had been in previous sessions. The RE71Rs are still soft, and have about 4/32nds left (rough average). But the grip just isn't there." that is the thing though, we cannot tell the grip wasn't there by looking at the data in hand, especially when almost all the lines are identical..you might as well be reaching the limits of the RE71s since all those lines almost identical except a few places...and average corner speed hike on that 7500-8000 mark seems to be responsible for that (or combination with other factors I mentioned above)

In addition to that, we would expect the tires that don't heat cycle out perform better when tread is less , that's the exact reason why NT01s and many similar tires perform the best right before you see them corded or why people have their Toyo RA1s shaved.. now that totally is a different topic of course

Jake

Regarding the Camaro video, they're exactly right. We're not using these IR sensors to establish pressure, but to measure tire temps and temp gradients dynamically. There's no replacement for actually measuring your tire pressures, and we do that every session. Lately we've been happy with 33 psi, and dropped it even lower than that for some super-hot sessions.

I think we can both agree the data is not conclusively in favor of excessively heat cycled tires. I guess the only solution is more testing.

Based on what we've been discussing, we'll probably run a few more sessions on the current tires.

Originally Posted by glamcem

yes, I am aware of that but I am still not satisfied with my 10 hz external GPS receiver, both Qstarz and Dual XGPS 160 fail to give that kind of precision at corners..

I don't have any personal experience with Aim MXL2 but it seems like a solid option, no wonder why so many teams and TA cars I've seen have been using them.. it just costs too much

Yep, we're not looking to do the dual 50 Hz antenna level of analysis with this car. We're chassis testing, not tire testing.

As far as the cost goes, you've got to remember that price doesn't come from the electronics near as much as it comes from the hardened case, mil-spec equivalent connectors, Raychem boots, etc. You can absolutely piece together the same sensors from Sparkfun or Adafruit and log everything with an Arduino or RPi, but it won't survive. I know you already know that, but I just wanted to emphasize that fact for anyone else reading this.

[glamcem]

Originally Posted by PST

As far as the cost goes, you've got to remember that price doesn't come from the electronics near as much as it comes from the hardened case, mil-spec equivalent connectors, Raychem boots, etc. You can absolutely piece together the same sensors from Sparkfun or Adafruit and log everything with an Arduino or RPi, but it won't survive. I know you already know that, but I just wanted to emphasize that fact for anyone else reading this.

nope, I didn't know that, obviously you know your tools .. I am pretty sure race teams have their reasons for opting more robust equipment but for what I do (logging and monitoring some basic engine data and merging with video and GPS readings) it's a bit overkill since more expensive systems also read it from the same source which is OBD2/ECU in this case, I would love to see that car in person

[GSpeed]

Originally Posted by glamcem

nope, I didn't know that, obviously you know your tools .. I am pretty sure race teams have their reasons for opting more robust equipment but for what I do (logging and monitoring some basic engine data and merging with video and GPS readings) it's a bit overkill since more expensive systems also read it from the same source which is OBD2/ECU in this case, I would love to see that car in person

If you're ever down this way, you're welcome to stop by the shop!

Sorry I guessed wrong, you seemed to know your sensors and I didn't want to sound condescending.

Jake

[solidONE]

^ About the RE71R. @PST Funny thing is that there are people claiming these tires offer as much grip as Hoosiers. They're also penalizing car equipped to this tire and the Rival-S as if they were running slicks in TA competition. Sounds a bit far fetched to me, but I've never tried these tires before. Do you agree with this assessment?

[GSpeed]

Originally Posted by solidONE

^ About the RE71R. @PST Funny thing is that there are people claiming these tires offer as much grip as Hoosiers. They're also penalizing car equipped to this tire and the Rival-S as if they were running slicks in TA competition. Sounds a bit far fetched to me, but I've never tried these tires before. Do you agree with this assessment?

I don't want to speculate yet, but we will be running Hoosier R7s on this car in a little bit, after we're done with the "street car" phase. We'll definitely have lots of back-to-back data to look at.

[solidONE]

Originally Posted by PST

I don't want to speculate yet, but we will be running Hoosier R7s on this car in a little bit, after we're done with the "street car" phase. We'll definitely have lots of back-to-back data to look at.

Awesome! Thanks for sharing all this data with us!

These same people have also insisted BBK upgrades and sway bars offer no performance enhancement, so I'd rather get opinions or confirmation from more reputable sources. If you catch my drift. lol Keep up the good work!

[Alan]

Originally Posted by glamcem

that's 60 heat cycles, I'd be happy if I can get 25-30 HCs from my Z214s
like I mentioned in my above post heat cycle is not probably your concern, if you want the best of both worlds I'd simply get another set of wheels, wrap them with NT01s and use them during the track season on both track (and drive to and from track) since they typically last about ~10,000miles (100TW) without heat cycling out, assuming you don't put crazy amount of miles when DDin during the summer... keep in mind this is an R comp tire so you probably don't ever heat cycle out your RS3s

Thanks for the advice. I'm not following your last comment. What do you mean by "keep in mind this is an R comp tire so you probably don't ever heat cycle out your RS3s"

I am struggling with the move to R comps. I don't feel like I'm at that skill level yet. But maybe it makes sense given the amount of track time I'm getting.

[glamcem]

Originally Posted by Alan

Thanks for the advice. I'm not following your last comment. What do you mean by "keep in mind this is an R comp tire so you probably don't ever heat cycle out your RS3s"

I am struggling with the move to R comps. I don't feel like I'm at that skill level yet. But maybe it makes sense given the amount of track time I'm getting.

I meant to say even some "mild" R comps like NT01 may not heat cycle out so the changes are RS3 won't ever HC out sorry for the confusion..

if you haven't already, you can definitely try the NT01s they don't have the shortcomings of the more aggressive R comps but still offer a lot more grip and treadwear for the money, but if you don't track as much (a couple track days during the season) RS3 or equivalent tires make sense

[glamcem]

@PST below is what I read on Miata forums :

They are extremely fast and wear extremely quickly. Expect them to wear 2-3x faster than an RS3 or Rival (non-S). IMO, not a good option for HPDE guys. The Maxxis RC-1 or Nitto NT-01 is slightly slower but will wear much better than the Rival S or RE71R.

I laughed when I heard someone mentioned : "if the RE71R tires have 200 TW, ratings NT01 have at least 300 TW".

if this is true, I am not sure how the RE71Rs can be still listed as "street" tires with 200 TW ratings, how can a street tire (Extreme Performance Summer tire) beat a DOT Approved R comp with 100 TW (or less)? .. it cannot

I mean we know those ratings may vary since they're not regulated like crash tests and we take the manufacturers' word for them but still .. we're talking about a huuge I mean huuge performance difference ..no wonder why RE71s beat the crap out of the competition in those comparison tests.

surprisingly (!!!) many organizations require 200 TW tires and looks like RE71R fits the bill for using "Street" tires in that specific class , I've also learned that tire manufacturers can use lower TW for their ratings but not vice since they can be sued for that.. so I wouldn't be surprised if Bridgestone gets sued because of that, if all is true of course

[stugray]

Originally Posted by PST

Lately we've been happy with 33 psi, and dropped it even lower than that for some super-hot sessions.

With all the talk about high tech datalogging, have you tried the oldschool tire check using chalk up the sidewalls?
I "inherit" used Hoosier R7s from my brother who has a racecar about 500 lbs heavier than mine.
He runs them at ~32 PSI so I started there.
But after checking with chalk, I see I can go down to about 22 PSI.
Then after getting 1.5 inch wider wheels with the same tire I was able to go down another 2 PSI.

Originally Posted by PST

As far as the cost goes, you've got to remember that price doesn't come from the electronics near as much as it comes from the hardened case, mil-spec equivalent connectors, Raychem boots, etc. You can absolutely piece together the same sensors from Sparkfun or Adafruit and log everything with an Arduino or RPi, but it won't survive. I know you already know that, but I just wanted to emphasize that fact for anyone else reading this.

That's funny, because my datalogger is built from components from Sparkfun (I actually drive by their warehouse every day).
The IR sensors I am considering (MLX90614) are also from Sparkfun, but are likely the same as the sensors in high end handheld units.
For those units you can set the emissivity of the thing you are measuring AND it has an internal temp compensation.
So I am guessing measurements will be within a few degrees absolute, and tenths of a degree relative.
I do aerospace for a living, so building it into a ruggedized unit is standard.

[solidONE]

Originally Posted by glamcem

@PST below is what I read on Miata forums :



I laughed when I heard someone mentioned : "if the RE71R tires have 200 TW, ratings NT01 have at least 300 TW".

if this is true, I am not sure how the RE71Rs can be still listed as "street" tires with 200 TW ratings, how can a street tire (Extreme Performance Summer tire) beat a DOT Approved R comp with 100 TW (or less)? .. it cannot

I mean we know those ratings may vary since they're not regulated like crash tests and we take the manufacturers' word for them but still .. we're talking about a huuge I mean huuge performance difference ..no wonder why RE71s beat the crap out of the competition in those comparison tests.

surprisingly (!!!) many organizations require 200 TW tires and looks like RE71R fits the bill for using "Street" tires in that specific class , I've also learned that tire manufacturers can use lower TW for their ratings but not vice since they can be sued for that.. so I wouldn't be surprised if Bridgestone gets sued because of that, if all is true of course

Comparison tests? Can you link? I'm sure the RE71R and Rival-S were developed for just that purpose. To cheat the rule books and win comps specifying 200TW tires. I remember the RS3 V1 used to be 140TW. They changed the rating on the V2 to 200TW to cheat the rule books. Lol

[glamcem]

Originally Posted by solidONE

Comparison tests? Can you link? I'm sure the RE71R and Rival-S were developed for just that purpose. To cheat the rule books and win comps specifying 200TW tires. I remember the RS3 V1 used to be 140TW. They changed the rating on the V2 to 200TW to cheat the rule books. Lol

you ask and you shall receive

http://www.tirerack.com/tires/tests/...y.jsp?ttid=202

here are some more if interested
http://www.tirerack.com/tires/tests/...y.jsp?ttid=198

[ame="http://youtu.be/kKbiR7sBQqI"]https://youtu.be/kKbiR7sBQqI[/ame]

if you think about it , there's no real magic there ...softer the compound lesser the treadwear will be, if I hear something like higher TW rated tire outperforms or equally performs with a lower TW rated tire, I find it harder to believe and I think people's experiences generally proves that

[stugray]

Thought that this would interest those on this thread:



http://arstechnica.com/cars/2015/08/...for-formula-1/