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What air pressure range for Hoosier SMs?

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#1
Flyntgr

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I usually ran my RA-1s at 38 psi, but I wonder what pressure(S) the Hoosier SMs run best at? My main track is a tight, technical 1.8 mile track with only 2 straightaways and 14 turns, if that matters. Thanks.

#2
James York

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I usually ran my RA-1s at 38 psi, but I wonder what pressure(S) the Hoosier SMs run best at? My main track is a tight, technical 1.8 mile track with only 2 straightaways and 14 turns, if that matters. Thanks.


Reggie,

That's why you test.... Run a test day before a race and take data. Air pressures are somewhat driver, track and setup driven. I am sure Hoosier can give you a "generic" start point if you give them a ring.

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#3
Ron Alan

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Reggie,

That's why you test.... Run a test day before a race and take data. Air pressures are somewhat driver, track and setup driven. I am sure Hoosier can give you a "generic" start point if you give them a ring.


A polite way of saying "spend the money and figure it out for yourself" :D

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#4
James York

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A polite way of saying "spend the money and figure it out for yourself" :D


Not really. Everyone always thinks there is some magic bullet numbers for anything we can adjust. There is a different answer for everybody.

Five minutes on Hoosier's website gives a starting range pressure with some input on adjustment. How hard was that? And to dial in his number, for his car and his track, requires testing to zero in on the best value. Or just run the Hoosier recommended figures and that is probably good for 90% of the drivers seat of the pants G-meter. If you not running at the pointy end in nationals, its probably good enough.

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#5
Gatoratty

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http://www.midatlant...r_tire_tips.htm
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#6
Gatoratty

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The above link says everything I have ever been told about curing the tires and setup.
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#7
Tom Hampton

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Much of the same information, plus a little more:

http://www.tirerack....nty/HOOSIER.pdf

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pitbull113

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http://www.midatlanticmotorsport.com/hoosier_tire_tips.htm



http://www.tirerack.com/images/pdf/warranty/HOOSIER.pdf

Wow, big difference in recommended hot pressures in those links.

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#9
Flyntgr

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Thanks for your replies. I had the tires a week or 10 days before my last race and before the break=in and the race, I read both the sites sent by gatoratty and Tom prior to asking my original question. NOTE the conflict, however.

One site is generic Hoosier (advising higher than usual RA-1 pressures)and the other is A6/R6 specific, which recommends lower than RA-1s. The R6 specific info says to set HOT pressures from 31-34+. I had time to heat cycle the tires EXACTLY as they recommended, and they felt awesome on the last two laps. So, I then set the cold pressures per instructions, in the middle of the high and low COLD setting recommendations and let them set for a week. At the track I practiced with them at the cold settings, and adjusted the hot pressures to fit the 31-34 bracket with the result of 1:27 fastest, which is comparable to the RA-1s in this hot 95+ temps. In the race later that day, I had set them to 33 psi HOT, which is only 1lb. lower than the highest HOT pressure they recommended,viz, 34 psi (plus). They were NO BETTER than RA-1, and probably worse.

MY initial conclusion, which prompted my question: they needed at least 37-38 psi JUST LIKE THE RA-1s.

Please LET ME REFINE MY QUESTION: What should be the range of HOT temps on a tight 1.8 mile track like Barber or ciruit Grand Bayou? (Low-high maxs in hot weather on rough asphalt). Maybe this additional information and clarification of my question will make your answer harder/easier. I had done my homework, but I still don't know the max-min HOT temps for mid-90 ambient temps in the South. Thanks again.

#10
Gatoratty

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And yet another one with different hot pressures.
http://www.racetire....ucts/tctips.htm
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#11
Flyntgr

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And yet another one with different hot pressures.
http://www.racetire....ucts/tctips.htm

AHAA! Gatoratty, that is the Answer I've been looking for : hot temps 180-200 AND 35-38 PSI! My tire temps were much lower: 156 low to 176 high, from coldest reading to hottest reading-not on the same tire of course. So, I need to increase pressures and monitor temps. I can do this, now that I see they CAN go hotter than 34 degrees and I know the temp range is up to 200 degrees. These tires are new to many of us-certainly to me, as they are my first set. Live and learn. Thanks to all.

#12
James York

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AHAA! Gatoratty, that is the Answer I've been looking for : hot temps 180-200 AND 35-38 PSI! My tire temps were much lower: 156 low to 176 high, from coldest reading to hottest reading-not on the same tire of course. So, I need to increase pressures and monitor temps. I can do this, now that I see they CAN go hotter than 34 degrees and I know the temp range is up to 200 degrees. These tires are new to many of us-certainly to me, as they are my first set. Live and learn. Thanks to all.


Reggie,

If you are not heating the tires to operating temp, you are not working them hard enough.

I don't think you will see the results you are looking for at the combinations you list above. Also, if you are taking temperatures by yourself, in the paddock, you are wasting your time. Flying into the hot pit and having a person standing by to take them is marginally useful, but not great.

You have seen three different "sheets" from Hooosier. Why don't you just call and talk to one of their tire engineers?

Also, don't be surprised if can't see a difference in ultimate "best" lap time from the Hoosier to RA-1.

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#13
NigelStu

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Reggie,


You have seen three different "sheets" from Hooosier.




I would say that THIS is the exact reason why the OP was asking for a good starting point from other SM racers. By the book/numbers/generalizations on a type of tire across different platforms, you are going to get vastly different recommendations and are just as lost as if you gave a 5 year-old an air tank, pressure gauge and told them to set the pressures. If the Hoosier engineer doesn't have experience with a SM, he will likely refer to the in-house recommendation, or the same thing that you can get from the web.

I KNOW there are a few SM guys running SM6s now - there is probably a consensus on decent starting pressures, which will give OP a good starting point. Lets hear it!



That being said, of course you need to test and tune to find the optimum cold/hot pressures that suit the driver, car, track and ambient condition - Its just a bit easier when you can start within a PSI or 2.
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#14
Jim Drago

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I ran them on a 99 SSB miata in 09. I ran at 33/34 hot and the tires did really well for me there. But I am sure we will try from 28 hot to 42 hot and see what we end up with next year as will many others. So regardless of what engineers and ITA miata drivers tell us, our class is very competitive. So the optimum pressure will come out, well an optimum range. That may be somewhat subjective as well. I know many ran the R888 at 28 lbs, I ran then at 42/44 psi hot.

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#15
davecarama

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I KNOW there are a few SM guys running SM6s now - there is probably a consensus on decent starting pressures, which will give OP a good starting point. Lets hear it!

That being said, of course you need to test and tune to find the optimum cold/hot pressures that suit the driver, car, track and ambient condition - Its just a bit easier when you can start within a PSI or 2.



FYI, SM6 is an R6 stamped with SM6 on the side. The tires are the same. Same compound, same internals. I have spoken with Hoosier about this on many occasions over the past few years.


For the SM6 on your Miata, start at the pressure the door jam says, 27 PSI cold, all the way around. You will see hot pressures in the 34-36 psi range hot. That is a good starting point... but I doubt will win you races.

Why so low? The RA1 has a super soft sidewall compared to the Hoosier SM6. You want to generate enough heat to make them sticky, but you want them to last a full session without feeling like they are getting greasy. So start at 27 and look at your lap times for the full session, and note where your fastest lap is. If you are peaking later than you want, add air, if you are peaking too soon, take some out. Test again to see how that effected your lap times.

If I start at 27# and by lap 7 to 10 I am making my fastest times (all laps within < .5). I know a guy in TT starting at 38#, getting his fast times by lap 2 and coming in because his times are dropping significantly after that. I know another starting at about 20# and winning races. It all depends on your driving style and how you like your tires to feel.
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#16
James York

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I ran them on a 99 SSB miata in 09. I ran at 33/34 hot and the tires did really well for me there. But I am sure we will try from 28 hot to 42 hot and see what we end up with next year as will many others. So regardless of what engineers and ITA miata drivers tell us, our class is very competitive. So the optimum pressure will come out, well an optimum range. That may be somewhat subjective as well. I know many ran the R888 at 28 lbs, I ran then at 42/44 psi hot.

Jim


My point said better...

Start with Hoosiers recommendation and spend a day going up and down.

Unlike Jim, I ran the R-888 at 33 hot. Classic exmaple of what worked for him didn't work for me.

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#17
Glenn

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The good news is that the Purple Tire guys are at the track, at least her in DC and the SE, and they will be selling THEIR tire, so ask them. I bet you find very informed answers.

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#18
Motor City Hamilton

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As you are seeing, there are a wide range of pressures being run with the Hoosiers. I have been using them for a couple of years and love them. I have run between 26 and 32 starting pressures, depending upon weather and other things that I'm trying in my setups. Heat of the summer this year I am at 28 or 29 front and 27 or 28 rear. Hot pressures around 35 or 36.

Gives you a place to start.

#19
Flyntgr

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Thanks for the numbers. I'll start low and work up 1 lb at a time!

#20
Motor City Hamilton

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Thanks for the numbers. I'll start low and work up 1 lb at a time!


I know guys using the SM6 on ITA Neons. They are starting 24-28. If you start in the 24-26 range, be careful on the first lap as pressures build. I tried super low settings and didn't find more grip, just more waiting time before I could hammer on them. 28's been my sweet spot.




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