Warm Tire Pressure

[roadracer162]

Just a little information. Homestead taking place in December can be in the upper 50's range to sometimes 80's. Go with the recommend pressures given by Frank Kinsey or speak to Greg Melka. He is always helpful with stuff like that.

As far as tire life goes, plan to do up to 7 practice session on Saturday before racing your three races on Sunday.

I smile at the remark that you "won't be using all the available traction" - I beg to differ. It seems that Amateurs tend to crash more than experts all the while experts are turning faster times. I believe that Amateurs will use all the available traction right up to the point that they crash. The difference is the expert can maintian a higher level of speed(use of traction) and do it more consistently than the Amateur.

Mark

[Sig]

My point with the temp is........cold is never consistent.......while hot can be.

[Toves33]

I am going to swap tires out at the end of Satrurday. This way, I have a fresh set going into the first practice on Sunday.

Sig, I see your point about what defines checking your tires "cold." What temperature defines that? My original question was in reference to checking the tires while the tires are warm with the tire warmers. After reading all these posts, it seems as though no one does that. I just thought I would ask. I like this forum because I am getting some great advice from all the veterans of racing.

[Super Dave]

I'll state this again.  Someone will have to tell me if I didn't say this, but...

Different manufacturers do different things.

Pirelli specifically states their hot tire pressures.  That is how you check them.  You'll have to have a basis of the heat in your tires from loading them up under traction to have any kind of basis for setting the tire pressure before you go out to ride.  Example, if a particular Pirelli tire requires 29psi hot, you're going to assume an increase in your tire pressure from cold.  Might be 3psi, might be 5psi. 

Michelin specifically states their cold tire pressures.  That is how you check them.  You'll check them cold, then you'll use the tire.

Methodology for checking tire pressures is derived from what the manufacturers find is effective for their carcass and compound.

[Toves33]

I believe you said it right the first time. I just wish there was less science behind checking tire pressures. There are so many factors that come into play. The temperature, the track, and the bike set-up all factor into what the tire pressure should be. I guess it is cut and dry for street, but racing is a whole different ball game.

[tstruyk]

nitrogen is an option...

here' s a decent read, most of it is covered but as I read it I found some interesting info...

http://nationalprivateer.com/Racetirepressure.html

[HAWK]

There's a lot of myths about nitrogen out there and the one in that thread is completely untrue. ANY gas will heat and expand resulting in a higher warm pressure and nitrogen is a gas just like any other. Nitrogen is used in tires and suspension components because it is a DRY air (the result of careful processing, ordinary compressed air can be filtered and dried as well). It has no moisture or oxygen in it like the air around you or from you air compressor. This can help to reduce deterioration of the rubber but we change tires so often that this is really not a concern. BTW the air you are breating right now is about 75% nitrogen.

[tstruyk]

does nitrogen expand less than air?  This is above my pay grade...

[Toves33]

That was a good link for tire info. Dave pretty much explained all of that in a short paragraph.

[HAWK]

Different gases do expand differently but for the sake of tire pressure the difference is almost unmeasureable. It has been way too many years since I took physics but remember that air is 75% nitrogen anyway so the difference is going to be minimal as long as you aren't using an air source that has a lot of condensation in it (water vapor will have some effect).

[tstruyk]

doesnt compressed air contain a high amount of moisture in it?  I thought that was the main point.  I really dont have a stake in this, just looking for accurate info.  I've got bigger issues than TP LOL

[benprobst]

Different gases do expand differently but for the sake of tire pressure the difference is almost unmeasureable. It has been way too many years since I took physics but remember that air is 75% nitrogen anyway so the difference is going to be minimal as long as you aren't using an air source that has a lot of condensation in it (water vapor will have some effect).

Under race conditions and on tire warmers we were getting between 3 and 6 lbs of air pressure increase using standard dry pressurized and un pressurized air (i.e. bicycle pump). While we were getting .25 - 1.5 increase using nitrogen. On an extremely accurate gauge. To say the differenece is unmeasurable is incorrect. Unnecesary maybe, but not unmeasurable.