need a quick clarification on tire PSI

R

Rabid Fishie

New member
So we kinda discussed this topic in another thread about pilot Pure's which I am now running. When you guys are stating pressures on here, the number listed is the PSI you are desiring when hot? I am really trying to work with pressures in order to improve handling up in the twisties. It was recommended for these tires to run 36f and 34 rear. Prior to my ride I set the tires and 32f and 31 rear in order to allow for increase with temp. When I was in the middle of my ride I check the pressures and they were up around 40. So my questionis, should I be starting at around 28 cold and shooting for the 36/34 hot?
Obviously ambient temp and road temp play a role, but when you guys state PSI on here, you are referring to hot PSI correct?
 
I've read alot of guys say take it hot, Elton Is a avid track rider, and while I don't always get along with him, his technical advice is Always Sound, and I respect his experience on the track.... Hopefully he'll pop in here and give you some advice.
 
well...i check tire pressures before i leave my driveway and the tires are cold just to make me feel comfortable and confident...
track days and racing its a different world and i leave this up to the more experienced guys though...
 
unless you have tire warmers you cannot be exact on the temp of your tires each time you check them. while obviously the outside temp changes, it doesn't change by 100 degrees each time you check it.... unless you're flying that baby from antarctica to the desert!

the book says to take em cold, MSF classes tell you to take it cold, the numbers on your frame are the cold pressure temp.

If Elton is taking em when they are warm/hot and he's an avid tracker... I'm certain he's got warmers on them or some "control" to make sure his temps are stable when he adjusts the pressure.

for street riding and canyon carving...... take it cold before you leave and adjust it to whats in your book... I think it's 36 or so for the front and 34'ish for the rear but I don't have the book in front of me right now.
 
Usually advised DOT's max hot not more than 5psi. Target is + 3-5psi when hot.

example; SuperCorsa Dragons. I run Street/Canyons
(cold) 33/32.... (hot) (canyons) they avg. 36/36
TrackDay's (cold) 29/29 (hot) 35/34

Slicks are different story.. You target the needed pressure when "hot" + slicks specially the rear run lower pressures any way's..

I don't have much experience with slicks, so I'm sure somebody who does will chime in and inform us/me..

Michelin Pilot Powers are a rule to themselves.. According to every Mich Rep I've talked to, they advise 36/36 even 38/36 cold and not to worry about hot temps.. Apparently from what I understand, this is due to sidewall construction.

And remember, this is just my humble opinion & opinions will vary..

RC
 
Thanks for the thoughts. I did try and figure for 3-5 PSI increase in the tires the other day, but I guess it was hot enough where it jumped about 7 PSI. Even at 40 hot they still stuck good. Keep the opinions coming.
 
I run 36 psi front & 35 psi rear cold for fast road use. I actually prefer 34.5 -35 psi in the front, but add in a little more so that I dont have to top it up so often.

The reason why hot pressures are important is so that you have a "hot" ballpark reference when you hit the track.

For example, if you ride super fast on the twisties and like the handling you get from a certain pressure, immediately check the hot pressure when you stop, so that you know what hot pressure to aim for at the track.

That will give you familiarity.

Once you're happy, let it cool and take a cold reading, from there you can get expansion rates...etc and infer more.
 
I agree with everything posted here. Street tires should be measured cold and run with the manufacturer's recommended tire pressure. Tire pressure is very important and should be measured before every ride. Even a few pounds either way can adversely affect handling dramatically. Running street tires lower than recommended PSI will not improve traction; in fact, it may very well reduce traction.

As has been pointed out, slicks are a completely different story. Slicks are measured when hot. Generally speaking, tire pressure in slicks should increase about 10% from cold to warm. Once warm, slicks should be kept warm throughout the entire day with tire warmers to minimize heat cycles. In order to be effective, slicks need to run at a minimum of 175 F. degrees. If you're not running hard/fast enough to generate this minimum amount of heat in the tires, you're better off running DOT tires. A simple way to test this is to measure tire pressure when you come off the track. You should need to bleed air off after each track session; especially in the morning. If you're not doing this, you're not generating enough heat in the tires to warrant running slicks.

Slicks are designed to run a lower PSI than DOT tires. Most, (but not all), DOT tires run at about 30 PSI, give or take. Like DOT tires, slicks vary between manufactures. I run Michelins. 29 or 30 PSI in the front; 24 to 26 PSI in the rear, depending on track temperature. When it's colder, I run 24 PSI for added traction; once the track is warmed up, I push the rear up to 26 PSI and the front up to 30 PSI. These temps are measured hot.
 
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