Noob Q about Tire Temp

[bigreid]

I've seen warmers that are adjustable and all of that.  How do you even know what temp to set them at or what temp your tires should be?

[Jeff]

it depends on the tire really.  somewhere between 160-180 deg F is typical for optimal traction.  Check with your tire manufacturer and they can tell you.

[Super Dave]

Michelin race tires are usually 140 front, 180 rear.  You're not just heating the tire, you're heating the air in the tire and the rim.

[catman]

Hey Dave how about supercoarsa's temps? was thrilled to see ya on TV supersport race this weekend! john in nj

[Super Dave]

Hey, thanks!  Wasn't happy with my position at all.  I guess that's what 10 laps of practice yields.

Pirelli's don't seem to need as much temperature or as long.  That I know.  I'm only guessing that it's it's around 135 degrees.

[bigreid]

Do manufacturers put out a chart or something like that?

[Super Dave]

Not that I know of.  Even then, it's always best to ask questions of the race distribution tire guys.  Tires change during the season.  The appearance might be the same, but the construction can be very different...heat needs can change then.

[catman]

Hey Dave -K3 best explained to me that keeping the temp at 10%   (close approx) from the cold pressure (from tire vender) is right, can you tell us,do you remove air to stay at the 10% # as the track and ambient temps go up during the day? (and add IF temps go downdown) I had a slippery session that sent me off track at summit-i like to avoid this,am interested in how we should treat our tires for best performance- Am switching to slicks from here on and just bought a Hot Box to help( digi-adjust tire warmer box.TIA John in NJ  Forever a noob until i can beat HAYDEN!!!

[Super Dave]

I'm not sure if you're asking me a question or making a statement.

I have pressures that I use.  As the ambient temperature changes, I'll check my pressures cold.  I find that I have time during the day to do that.  going from 33 to 30 PSI in a front tire can have a dramatic affect on how it works and feels.  Similarly going from 22 to 20 or 24 can cause the tire to be used up quicker or cause it to have less grip.

Even having a tire guage that doesn't read properly can cause these kinds of problems.

[catman]

Yea Dave-sorry its mostly question- to start( and i gotta say i am appreciative of this,thanks in advance) you stated as the ambient temps change, you  check the cold temp-i am cornfused i'll admit- i have it figuered that i set the cold temp say 30 lbs for this example( or  to distributors #s) and as the day (usually) gets hotter,and pressure goes up, i should release until i am at 33 lbs (at rise of  10 %) of cold temp setting from original 30. Then i get to wondering if a lower degree cold setting  changes the equation at all, - since i have been such a part timer, i would like to keep the learning curve out of this ,its very hi on my priority list!I think K3 explained it the best ive heard to date because he understood my question or better,misconceptions as an ongoing noob- wanting to stay safe mostly(dealing with the variables that i can control somewhat.Any way , i'd like to hear your explanation,i know that suspension is right, -just a question about the above- Hope i asked the right questions- TIA again ,John in NJ

[HAWK]

Your tire vendor can get you to a good starting point on pressures but in the end the final setting is the one that you like. Check your tires when you come in from a session. Are they hot, too hot, cool?  If your tires get too hot then they will get greasy and start sliding, not hot enough and you'll be slipping for a different reason. With the cool temps Saturday morning at Gingerman last month I started about 2 PSI lower than my normal pressure and the tires worked well all morning, about halfway through the GT lights race however I started to spin the rear exiting the corner and when I got in the tire was really hot so I went back up those 2 PSI and the tire ran a little cooler and hooked up like I expected. If you let air out as the conditions warmup you are doing 2 things at once, as the tire warms up it gets softer and needs the extra pressure to support itself and not overheat. If you let air out then you are going to get even hotter. Take notes about your sessions, outside air temp, tire pressure and temp and how things felt. Then use those notes to set your cold tire pressure for the day, if you need to adjust your pressure while the tires are hot then go up or down 1 PSI to get what you want. Always set your tire pressure cold.

[catman]

Hey Paul- got the keep records, make small changes(1lb) & feel the front(i do) instructions, when i got the chance (only raced a couple times this year ) I had a laser thermometer and leftside/right side of rear was different by 10 or so degrees- the right side was hotter cause at summit point  we go right alot- guess the priority should  be watching the  more volitile side- anyway your info is also helpful,better get a can of white paint,youll prolly be needin it for your 07 number plates (thanks) John in NJ

[HAWK]

Don't worry so much about side to side, The car guys need to worry about inside and outside for camber adjustment but as you realize left right is a function of the track. more rights more heat on the right side. Worry about the overall temp, is the hot side too hot? Starting to get greasy? not hot enough to work? The big thing though is don't change the pressure because it goes up when the tire gets hot, change it when something is not right.

[Super Dave]

Tire psi is a measure of internal pressure.  Catman, yeah, if it gets warmer out, the tire pressure will come up.  Then you need to reduce the pressure.  The pressure supports the tire along with how the carcass is manufactured.  You can go up and down in pressure to get the tire to "feel" like one wants.  But, honestly, I have seldom changed pressures much from recommended. 

Radial tires seldom get "hot".  If they do, it's a manufacturing problem or a specific problem related to the track and the bike.  The nice thing is that radials also work in colder temperature.  In the day of bias ply tires, tires didn't work in the cool, and they would over heat.  Tire pressure was a way to keep the tire carcass from moving around so much to reduce the tire's time from turning to junk.  Basically, the tire would be close to greasy all the time.

[catman]

Thanks all- I got out of this (other than previously acknowleged) that  if the day gets much warmer than starting temp,a small incremental lowering(if a there is a problem) is ok, and charting will help predict,better. I wonder if someone can recomend an air pressure gauge- I really appreciate ya helping out here Dave, Hawk etc. appreciate your time /response! John in Victory Gardens NJ

[benprobst]

My snap on / blue-point has been spot on for over 15 years, requiring only one adjustment following a ver hard drop and crush, wich actually only nocked it off by about a pound and a half.

[HAWK]

The actual accuracy of the gauge is not really that important as long as you always use the same gauge. If you were to walk through the pits and check your tires with everyones gauge you would be hard pressed to find 2 that read the same but if you always use the same one you know what you are running.

[catman]

thanks Paul,Ben- i look foward to next season as i,m sure we all do,and thanks to the guy who actually started the thread-John

[benprobst]

The actual accuracy of the gauge is not really that important as long as you always use the same gauge. If you were to walk through the pits and check your tires with everyones gauge you would be hard pressed to find 2 that read the same but if you always use the same one you know what you are running.

Not neccesarily. if your gauge reads incorectly in the first place then it is prone to changing. If the tire man says run 31 in your front tire, he means run 31 psi with a correct gauge, not whatever you drag to the track behind the truck. Sure you may think well its normally 3 over so ill put in 34, well like I said before, if your gauge is that far off in the first place then who is to say it wont be 1 lb of or maybe 4 lbs off when you go to use it next. getting good quality tools will pay off in the long run.

[catman]

Thanks Ben- i want to remove the variables and will look for snapon guy,or motionpro etc during the winter- i guess to check it out one could take a consensus of a couple of others and compare to know from the start if you have a good one - John

[HAWK]

Not neccesarily. if your gauge reads incorectly in the first place then it is prone to changing. If the tire man says run 31 in your front tire, he means run 31 psi with a correct gauge, not whatever you drag to the track behind the truck. Sure you may think well its normally 3 over so ill put in 34, well like I said before, if your gauge is that far off in the first place then who is to say it wont be 1 lb of or maybe 4 lbs off when you go to use it next. getting good quality tools will pay off in the long run.

Point well taken Ben, I don't by any means advocate using junk but getting the perfect gauge is also not necessary. I use one of the rather inexpensive electronic digital gauges that are easily  come by at any part store. The solid state strain gauges used in these gauges are rather reliable and, as long as the gauge manages to stay out from under the truck, will tend to be much more consistant than most of the mechanical bourdon tube type gauges.  

The point I was trying to make is that if I were to take your Snap-on gauge and measure my tire and then walk down the pits and find another Snap-on  gauge just like it I rather doubt that I would get the same reading. I see racers all the time using their buddies gauge, then next weekend using another buddies gauge. This is a very good way to have no idea whether you have more or less pressure in your tire than you did last week and therefore renders any notes you may have worthless.

BTW Catman, the gauge you want to check against is the tire mans. That's the one that counts.

[benprobst]

yup. re-read my post and kind of sounded like a jerk, didnt mean to, sorry. But yeah, if your going to use a cheap or cheaper gauge the two most important things to do (imho) would be to check it against the tire mans gauge at basically every weekend, and like you said hawk, use the same one over and over.

[catman]

Hawk -great point- i will compare the gauge with tire guys'gauge-  great point, but still appreciate ALL of you on this topic-John in Victory Gardens NJ

[K3 Chris Onwiler]

Yeek!  I don't trust digital gauges any more than I trust digital scales.  Either way, the gauge or scale at some point takes a "picture" of what it sees, and that is the number you see in the digital display.  Ever weigh yourself on a dial scale, and notice that your weight changes if you lean left or right?  What if the digital scale makes up it's mind while you're leaning to one side?  Now when you move back to center, the numbers on the digital scale don't adjust like the pointer on a dial scale.
The same holds true with a digital pressure gauge.  If you don't get the hose exactly set square on the valve stem first try, the digital gauge will read innacurately.  The dial gague will fluctuate until you have a good, solid seal, and then the needle will settle down.
The Lithium Motorsports team has a really neat gauge that they use at the track.  I think it's made by Mildon or Summit.  Obviously, it was made for drag racing.  The gague has 1/2 lb incriments.  I want one....

[251am]

 Accu-Gauge from Aerostich.com  It's a dial gauge with a pressure release button. Set your pressures cold as advised by your tire vendor. Say, in the morning, BEFORE you put the warmers on. Do not fiddle with the pressures with the warmers on, or after you've come off the track, or before you go out for a session. It takes some time after a session or race for the tires to cool enough to re-set the pressures correctly. I went through this with Tom Mason, a great Michelin vendor, as I had been adjusting pressures with the warmers on just before racing- a no-no. Check your gauge, on the tires, right at Tom's vending area after he mounts and balances your fresh rubber. Also, do not assume that slipping and sliding is indicative of improper tire pressures.

  There are a couple spots at Gingerman and one particular spot at MAM where the surface is well polished and will produce great results, as far as slides are concerned, if you're heavy on the throttle and drifting off the line. Then, there's the suspension possibilities to adjust for better gription....      It's a never ending tail chasing...   Notes in a designated book are a great thing.         

[catman]

HEY 251- WOW thats good - changing air pressure while its warm is prolly where my questions/problems arose! That and all your posts have helped so much and i will look up gauges based on these recomondations- K3's mention that lithium uses a certain brand(s) steers me that way,i will start there- BIG thanks to you all! John

[HAWK]

Chris, you are correct that improper usage will result in improper readings, this is however true of analog gauges also. When I adjust pressure I get the tire where I want it then take 2 more readings. When I can consistently get the same reading then I am satisfied, I do this with dial gauges also as they contain bearings (several) and gears which all add stiction to the mechanism.

Again the important point is to ALWAYS use the SAME gauge.


Oh and about that bathroom scale thing, most of the less expensive digital ones use a dial, like the number dial on an analog scale, that has a series of lines on it that are read and counted by an optical sensor so you are using an analog scale with a digital readout.  A true digital scale uses strain gauges (at least 2 sometimes 4) that are summed to the microprocessor to get a reading, these are almost completely unaffected by the angle that you stand at.