Thoughts from a racer on Michelin Tires...

Not much challenging though about walking over to the control tire the shade that you set that morning, and checking how much it went up with the increase in ambient temp.. and remember, you only need to even consider bothering with doing this if it's going to be a COLD morning and then get much warmer later. As Rob pointed out already, on a typical race weekend you would be using tires in the morning, then getting freshies mounted later anyway so what is all the worry about?.. I really just don't see the difficulty in checking psi before you put it on a warmer..

ALSO, what do all you "hot temp setters" do when you scramble to get wheels mounted with say 10 minutes before 1st call? how do you set a hot temp then??

 

Would never go out and race on a cold tire. I've got two sets of warmers and have used them both at the same time for situations kind of like that. Though never with a time crunch like that.

I had always ridden on Dunlops and we found that hot pressures and carcass temps were critical in getting them to work right at some of the tracks in our area. We would adjust tire pressure to suit the weather mostly. Our tire pressures at the beginning of the year when it is 40 degrees out differ quite a bit from when we would be racing when it is 95 degrees out. We would come in probe the carcass to make sure it was in the good range of heat then make changes if needed. It is easier to control hot temps then cold temps. I'm not sure how you could actually play with pressures throughout the day with Cold temps. You would have to let the tire cool completely to ambient temp. then remove the air right? Because 1 PSI out of a tire that is 190 degrees will not be equal to pulling 1 PSI out of a 50 degree tire. Right?

I don't see it being a bad habit. The more data the better. Also seems easier to control the variables.

 

Set it at 4psi lower than hot temps. I have done that several times and never had an issue. Obviously it isn't on the nat's ass, but it is pretty damn close.

Never say never.

Wait till you are sitting around at lunch in some shorts and a t-shirt, eating a BBQ sandwich, with your wheels and newly installed tires sitting the back of the truck, not really in a hurry because you are in race #2........and you hear "races #1 and #2 have been combined and this is 1st call".

I went out and raced at the GNF's with tires that had never seen warmers. They set the pressures at 4psi lower than hot pressures, i ran a hard warm up lap to scrub them in and raced.

 

Lets have everyone reread what Robbie states above.Michelin recommends 30F and 22R cold (Ambient temp).Every fast person i know that run Michelins follows what is stated above and dont have any issues with there tires.If you get the tires up to operating temp the pressures will go up 5 to 7 psi front and rear.And this range will offer all the grip and performance your looking for.If your getting a lower or higher psi then this you either didnt set your cold pressures to Ambient Temp and or have a set up problem or are using the wrong tire compound.The + or - psi that the Jensens and Matts make is a rider feel preference.This is just my 2 cents..

 

Anyone know what tires set cold, say 30/22psi @ 60 degrees, builds to at say 85 while not in direct sunlight? I set my "practice" tires at 28(16.5slick) and 21(190dot) in the morning and my "race" set during lunch. Never had traction or wear issues.

 

What? You have to adjust tire pressures? Why didn't someone tell me?

 

Hot,cold 1lb this way 1lb that way isn't going to make the average person lose or win a race because of it.

Michelin recommends 30psi front 22psi rear set cold.
How do you think we come up with the hot pressure we used......you start with the cold pressure the first time. Once it has been established what the hot temp is on the warmer and the temp off of the track then you have your baseline hot temps.

Now that your baseline hot temps are achieved you can play around with it and see what works best for you.

If i set the tire in the morning at say 60F and was still using that same tire in the afternoon when it was 80F and i never took it off the warmer. I know what my hot temp psi is and I can just bleed it down 1 or 2 psi.

It's not Rocket Science people

 

+1
Setting cold temps might work for Michies, but Dunlops definitely are picky about their hot pressues.

 

It is quite weird that the michelins work so well just by setting the pressure cold.

pV=nRT, p∝T if n,V are constant.

T1 = 60F(ambient) T2 =85F(ambient) T3= 150F(hot off the track)
Assuming V is constant
p1=n2T1, p2=n2T2, p3=n3T3

p1 to p3 = p3-p1=(n3T3)-(n1T1)
... if there are no leaks in the tire, so no air can get in or out n3=n1
p1-p3=(T3-T1)n1=150-60(n1)=90(n1)=δp1,3

Also,
p2 to p3 = p3-p2=(n3T3)-(n2T2)
... if there are no leaks in the tire, so no air can get in or out n3=n2
p2-p3=(T3-T2)n2=150-85(n2)=65(n2)=δp2,3

From looking at this, it would appear that δp1,3 would be greater than δp2,3 not only because δT1,3 is greater, but also because n1 is greater than n2.

Maybe setting the cold pressures works because the tires reach different temperatures "hot off the track temps" for different ambient temperatures.

 

Even I was offered to test a tire.

 

This is the only part of your post I understand! ...BUT..

I think temps are fairly consistent based off ambient pressures. When I used Pirellis a couple of years ago when "hot pressures" were coming into fashion, I could set them cold based on what they would become after cooling to ambient from the recommended hot pressure....That and Moose/Greg would say 28/25 cold which nearly always worked out to be 31/28 hot.(if my memory is right on specific #'s, but specifics don't really matter here.)

 

You forgot to account for the mechanical heat generated by carcass flex.

 

That is what created the "hot off the track" temps:up:

 

Robbie is on the same stuff as the rest of us. End of story. Ive traded tires with him along with plenty of other people. He is often swapping out tires with the michelin truck, they turn around and sell that right back to the regular racers.


Cold tire pressures work. They work differently but they work. Tell me what you want your hot pressures to be on your sliperellis and I bet I can get within a half pound on the cold pressure within a try or two. Half way through the season it would be dead nuts everytime. Its the same stuff, we are all looking for a feel at temperature, it doesnt matter when we checked the pressures. As for the whole morning vs. afternoon thing, first off if youre on the same set of tires on a big bike for that long youre doing something wrong besides how you set your pressures. Second, dont be ignorant, yes if you set your tires to cold temps in freezing ambient temps, then plan to run those tires 8 hours and many many laps later, go ahead and check the cold or hot pressures later in the day to make sure they are still in the proper ball park.