Tire warm-up procedure for trackdays: "Food for thought"

[Fish]

Gary,

Great tip. As a cheap bastard myself, I have been seen doing silly things like using the exhaust of my rig to act as a tire warmer ( put the bike on a stand near the tailpipe and slowly rotate the wheel like a pig on a spit over a fire).

Mind you, I have the fullest confidence in the compression and rings of the rig in question--blow-by and oil not good!

You will still see me do the 'weave' occasionally when I'm not near other riders though. It's not to warm the tires... more like a superstitious way of being sure any foreign grit or fluids have been scrubbed off. Keep up the great posts! I promise I won't quote you in my book without permission!

 

[gsxrpeter]

Gary i'm confused eithier I read over it or you didn't say it, but what about cold cutting the tire? This is idea wich i've heard from many racers of what not to do on cold tires trying to warm them up to quickly.

 

[Harpo]

Gary i'm confused eithier I read over it or you didn't say it, but what about cold cutting the tire? This is idea wich i've heard from many racers of what not to do on cold tires trying to warm them up to quickly.

What is cold cutting??

 

[gsxrpeter]

Cold cutting: This is when you have gp tires and don't let them properly warm up and you start harping on the throttle right off the bat. This shreads, the tire, cutts and all around shortens the life of the tire.

 

[kevo]

I thought that was cold tearing?

 

[gsxrpeter]

same difference

 

[Trackho]

Cold cutting: This is when you have gp tires and don't let them properly warm up and you start harping on the throttle right off the bat. This shreads, the tire, cutts and all around shortens the life of the tire.

Nope cold-tearing isnt usually caused by this. Every tire that I cold tore--approx 30 to date was warmed up for several laps. Seems that the Dunlops (240 compund) start at under 2:03(ish), for me, the Rennsports started at much slower lap times---All the rears were at T-Hill. The tire manufacturers---first blame it on suspension set-up, then on T-Hill's surface. The fundamental problem is that the tire never comes up to "working temp" and the polymers actual shear, instead of flowing--usually a softer compound solves the problem. My 758 compound(med) wore really well this Sat at T-Hill. For some reason, T-Hill seems to be the "killer track" for the rear, but is pretty easy on fronts. But, I have tore fronts at Buttonwillow and Sears as well---Go figure

 

[tlthehun]

Ideal Gas Law inaccurate due to moisture

T-ho,

using a very rough approximation (using ideal gas law)...

going from 40F to 65F will yield ~5% change in pressure -- assuming that there is no change in volume.

so if your initial pressure was 30psi at 40F, your looking at closer to 31.5psi at 65F ambient.

of course, it's been a long time...and I'm too lazy to verify my numbers and approach

The reason that we get different numbers in real life is that air contains water which doesn't comform to IGL and we see higher than expected pressure differences with temperature changes. That variable could be reduced by inflating the tires with nitrogen.

 

[afm199]

I guess with all this discussion I was sorry to see braking and accelleration underemphasized. On my warm up laps I gas it up and brake fairly hard (upright) as a means of tire warming I am very conservative in the first lap on turning, and somewhat conservative on the second. The older the tire, the longer it needs for warmup.

Oh, yeah, the only time I ever get to pass Tom Montano is on the first lap at track day when he is on slicks and I am on DOTs. Wheeeeeeee

Ernie

 

[axtman]

Actually IGL does a decent job. One needs to do the tire pressure calcs. in absolute pressure, ie psia instead of psig = gauge pressure reading, then subtract out the atmospheric pressure (14.7 psi) to get back to gauge pressure in psig.

For example 30.0 psig = 44.7 psia. Heat that tire's gaseous contents to 1.05 times its original absolute temp., you get 46.9 psia = 32.2 psig.

--axtman =

yeah.
I didn't want to take into account gas mixture and non-ideal behavior.

keep in mind that you can't just take the ratio of temperatures in Fahrenheit. I believe that the unit for T is in kelvins (0 C ~= 273k~=32F). Since all the constants divide out, the ratio would be Tf=65F=291.3k and Ts=40F=277.4k. Where Ts is the start ambient temp. and Tf is the final ambient temp.

Tf/Ts = 1.0501 ~= 5% increase

30psi + 5%*30psi = 31.5psi

NOTE: Black is a nice color for a heat sink...so, the tire will absorb energy from radiation.



EDIT: one last note...

pressure rise from Heating effects of friction/flex >>> than heating effects of change in ambient and radiation

^
|
|

qualitive explanation: final temp of the tire and thus, change in pressure, will be determined by how hard you are running and the track temp. This temp will asymptote well above ambient + heat due to radiation.


Sooo....set it and forget it.. What you need to do though, is account for your initial pressure set up. i.e.

*all things being equal* if you are used to setting up your pressure at 29/30psi on a 65F day, to get an equivalent mass of air in the tire on a 40F day, the pressures would be ~28/29psi

 

[mjrydsfast]

I like this post.

thanks.

 

[toxicity]

Great thread.
This should be a sticky.

I have never been on a track, but now i feel more ready, (less scared).

 

[kevo]

It *is* a sticky.

 

[SNAKE03RR]

Good info here. I use the Chickenhawks with my BT002's but the good thing about my track org(Reduc), is that they have a mandatory 3 lap warm up on your first session of the day with no passing. This really helps me when I'm breaking in a new set of tires.

But, the rest of our sessions have no warm up laps.


Lance

 

[mjrydsfast]

Warm it up Kris!

Good info here. I use the Chickenhawks with my BT002's but the good thing about my track org(Reduc), is that they have a mandatory 3 lap warm up on your first session of the day with no passing. This really helps me when I'm breaking in a new set of tires.

But, the rest of our sessions have no warm up laps.


Lance

Actually, they're ALL warm up laps for me, or that's what I tell people who say "Mike, you're goin' too slow man". I'd like to do an entire race based on only warm up laps. That way, I know I would never have to dress warm and risk having my leathers fit funny.

 

[jiker]

Tire Warmers

While not riding is it best to keep the warmers on the bike (keeping the tires continually warm) or 20 minutes before you go out turn the warmers on?
Do we want to reduce the heat cycles by keeping them warm the entire day?

 

[SNAKE03RR]

Re: Tire Warmers

While not riding is it best to keep the warmers on the bike (keeping the tires continually warm) or 20 minutes before you go out turn the warmers on?
Do we want to reduce the heat cycles by keeping them warm the entire day?

The first session of the day, I put them on about 40 mins before I go out there.

I keep them on as much as can between sessions to keep the heat cycles to a minimum. I used to unplug them every so often but they automatically shut off/on at temp so I usually let it go like that.

 

[neuera]

how does this thread apply to new tires? It's my first time at the track on july 2nd and I'm installing brand new tires over there. Its diablo corsas. do i just follow this or do i even take it slower for a longer amount of laps?

also what do i do to keep my tires warm during the different session breaks?

 

[Gary J]

how does this thread apply to new tires? It's my first time at the track on july 2nd and I'm installing brand new tires over there. Its diablo corsas. do i just follow this or do i even take it slower for a longer amount of laps?

also what do i do to keep my tires warm during the different session breaks?

If these "street compound" Diablo Corsa tires are going to be brand new when you first go out on track, in your first session at that trackday event, I'd suggest taking about 3 laps to gradually increase your lean angles, and do the warming/scrubbing of the rubber, before considering everything to be ready to go at your personal "fast" pace.

As for warming between sessions, for trackdays, it's not really something that you should concern yourself with Neuera. Just adhere to the gradual lean increase process (as described in the original post of this thread) for the first lap or so of each session, and the tires will come up to temp nicely, and you'll have a great day!

Gary J