I was thinking recently about tire pressures at track days and came up with a device.
Basically, my idea is to have a second valve stem that is set to release any pressure above X psi (X = your desired hot track temp). the thought is that before you go out on track you just inflate until the release valve opens (no gauge needed). then as the tires warm up on track they bleed off air so you always hold X psi until they cool down (you’ll fill tires again before next session). the device would be 100% mechanical with some sort of adjustment ring / screw
kinda, they have automatic deflators that are used in the off road world. Set what psi you want the tire, screw deflator on valve stem and tire deflates to that psi.
TRAILHEAD AUTOMATIC TIRE DEFLATOR
The Trailhead Deflator allows you to easily Air down to offroad tire pressures. Simply screw the deflators on to the valve stems and air will be released until desired pressure is obtained. These are Automatic deflators pressure can easily be adjusted with included adjustment tool Automatic Tire Deflator Comparison Kit is available in two pressure ranges 5-20 lb or 15-40 lb choose kit that is in range that you normally air down to below. Kit includes Leather pouch, Four Deflators, Low pres…
The counter point would be that a road compound race tire isn’t sticky until it get up to temp, so the tire being under inflated until they heat up isn’t that big of a deal. The pressure being low doesn’t affect if as much as the rubber being cold. And since you aren’t pushing the car until the temps are up, that’s why you haven’t seen this device yet.
not according to the people who use them on track cars… looks like I’m not the first to think of this.
from evoM:
[quote=“VR4orceCJ”"]
Yup… Longacre sells them… You’ll have to drill an 1/8" NPT hole in your rims and set the relief pressure. Never used them myself but know of others that do and they like them.
seriously though if one malfunctions you are fucked, also the complexity to keep a little pump in there that can re-inflate your tire once they cool down in a straight or something that involves little friction across the face of the tire to keep heat
Don’t let it just fly out, have a delay that it only lets pressure out after a pre-determined amount of time.
This way short increases in pressure would not “trigger” it.
This is already done on other applications.
remember, this is for track days and racing only… under race conditions you’re going to build up pressure after a turn or bump almost instantly since you’re already full out. (that’s why it’s in this forum).
they’re interesting looking, pretty much what I expected but thicker)
remember, this is for track days and racing only… under race conditions you’re going to build up pressure after a turn or bump almost instantly since you’re already full out. (that’s why it’s in this forum).
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Except there are times when you are saving tire, or trying to bring temps down and not going full bore, suddenly you lose a couple PSI that you cant get back, your temps drop out of optimal range and you’re driving on pure grease. A good idea, but not one that should be applied to the real world.
The key is being able to add pressure back which would be heavy and complex.
Maybe the hollow spoke Porsche wheels could be used as a resevoir and…
Nevermind.:mamoru:
i enjoy just keeping my pressures constant for a set, than adjusting if necessary by increasing. im talking of course about slicks, and track driving. since for track you want race temps or hot inflation pressure, whereas for other driving/street you want cold inflation pressure. id be hesitant about a mechanical pressure valve malfunctioning, theres probably a reason that lemans and such stick to 2 valve stems per rim, instead of 1 mechanical one…
remember, this is for track days and racing only… under race conditions you’re going to build up pressure after a turn or bump almost instantly since you’re already full out. (that’s why it’s in this forum).
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what? even if air didn’t change density with heat… as you ripped around a track your tire pressure would still fluctuate wildly.
