The science presented is fact. The experience presented is what feels better to various riders, under various conditions. Be safe out there.
what I learned about tire pressure
- Thread starter WWJD
- Start date
(psalm69 @ Sep. 29 2006,08:40)Nitrogen won't change pressure in spite of temperature? WTF? I'm not sure what planet you are living on, but clearly the physics there don't apply. Consult your clearly unused highschool chemistry book for the answer to that one. Let me give you a hint it's called Charles' law. The only reason N2 is used in tires to to prevent a moisture build up from condensation thereby negating any balance problems at high speeds or in the case of aircraft to prevent unwanted corrosion. You clearly do not know what you are talking about. It is that kind of misinformation that gets guys hurt. No you really aren't that sophisticated.(WWJD @ Sep. 29 2006,05:28) Engineers? I never found riding at the track. I'll look harder next time, and consult him when I find him. Until then, I'll listen to the droves of multi-year experienced track riders, racers, instructors and professionals. They'll have to do in a pinch.
My numbers are by NO MEANS the ULTIMATE for everybody. They work for me. Any many people have no idea they can and should lower their PSI for better grip at hard lean. You COULD stay upright just fine at 42, but why not tilt the odds in your favor? My mian point was TOO LOW gets weird. I never experienced it before, now I have, so I'm passing it on
There's the whole "Nitrogen filled" thing where the tire pressure doesn't change from heat... but I'm not that sophisticated
My point? Unless you have data that backs up an assertion it is just an opinion. Don't present it for more than it is.
Rongotti
Registered
Yall calm down I know psalm69 and go to the track with him often! Since I lost my busa to my wife in the divorce, I just go to watch and take pictures. I offer this as proof to his claims of being a hayabusa master of track days! So know that you all can plainly see he is a riding master, I expect you all to show the man some respect for his extensive knowlege! and skill
ww you are missing my point ..higher pressure make for better feel (or something like that) the reason you (or anyone ) would lower pressure would be to heat up the tire .expanding the inside.getting the outside nice and sticky.if you can really put the tire through a heat cycle,bye riding hard many laps around the track, street or whatever .than sure lower the pressure you need too.but the other 95 % of people WILL NOT GET GET INTO THE TIRE ENOUGH.and should keep the pressure higher.on the track or street they will feel the bike more and still get the tire buggered up (just not what yor thinking.)the guy that everone slammed was right for someone just out doing a track day..they should LEAVE THE PRESSURE ALONE they already know the feel of there bike.if they get sloppy and and dont take a lap or whatever egresive they would loose what sticky ness the lower pressure would of got themanyways .ps i only run battlax 56 at 40 psi and can open a can o fwhoop arse on many of fellas with tire warmers and buggered up tires on the street or track. and i dont ride hard.ps watch some poser slam my penmanship but not be willing to ride with me!!!
So do you evacuate the air out of the tires.?To 500 microns or what? Then apply the nitrogen???I'm so confused
forceofnature
Registered
Air is 80% Nitrogen the other 20% is Oxygen and other gasses. Nitrogen as a gas is a larger molecule and will not penetrate the rubber as much and does not oxidize materials. Pure N2 does not have the moisture issue.
With that said. Pressure retention would be only slightly better. With large aircraft tires I can see a benefit. Volume is large and the temperatures cause the pressure to increase rapidly while landing. This is due to heating and landing impact.
tinbender0 speaks of temp/pressure correlation, well every gas will increase a given amount for a given volume and temperature change. Nitrogen is used most be cause it is easiest to extract. Think about it. 80% is present in the air.
I have been working with gas chromatography for years. I may have to bring in the scientific evidence if there are still doubters.
BTW I keep my tires at 38- 42 lbs in the street. Works for me.
With that said. Pressure retention would be only slightly better. With large aircraft tires I can see a benefit. Volume is large and the temperatures cause the pressure to increase rapidly while landing. This is due to heating and landing impact.
tinbender0 speaks of temp/pressure correlation, well every gas will increase a given amount for a given volume and temperature change. Nitrogen is used most be cause it is easiest to extract. Think about it. 80% is present in the air.
I have been working with gas chromatography for years. I may have to bring in the scientific evidence if there are still doubters.
BTW I keep my tires at 38- 42 lbs in the street. Works for me.
Well ,well ,well, dry nitrogen is used for pressure testing lets say "air conditioning refrigerant lines" instead of other available gases available because of its temp/pressure stability, EPA requirements, and for the hydroscopic adhesion! Also...this being said ,,in a Air conditioning system that requires 500 microns or less to be desired.. I'm sure using it in tires the temp/pressure diff. would be minimal....C'MON back one time now Ya hear
Rob T, I think he was more than a little rough, really, re-read those comments.
MC, thanks for unlocking thread.
The rest, I change mine(psi) alot, maybe too much. I'm not a tire wis. I just noticed things as I rode more over the yrs. The tire, tire wear, cold day, hot day, playing hard, playing hard 2-up, interstate w/or w/o 200lbs. of gear. I guess it's what works for good to you. Feeling confident in your bike/tires is half the battle, maybe alot more than that. Thanks again WWJD for the info I thought it was just me playing with them alot, off track anyway. Alot of street riders around here couldn't tell you what they run for psi on any given day, oh well.
MC, thanks for unlocking thread.
The rest, I change mine(psi) alot, maybe too much. I'm not a tire wis. I just noticed things as I rode more over the yrs. The tire, tire wear, cold day, hot day, playing hard, playing hard 2-up, interstate w/or w/o 200lbs. of gear. I guess it's what works for good to you. Feeling confident in your bike/tires is half the battle, maybe alot more than that. Thanks again WWJD for the info I thought it was just me playing with them alot, off track anyway. Alot of street riders around here couldn't tell you what they run for psi on any given day, oh well.
GHT? A couple minutes of the next session any surface is very different, smoother, a lot more trust worthy.
For the PSI before them up first one. I checked they wil heat up fine is very
Track surface is very different, smoother, a lot more planted to lowest limits if PSI a tad. only 3 laps. It sucked! Now I know what topic. Cold day at them heat up and I lowered they only went:
It was cold, tires to 30 like normal thinking the time. But if you can't recommends 42 front and went
For the PSI before them up first one. I checked they wil heat up fine is very
Track surface is very different, smoother, a lot more planted to lowest limits if PSI a tad. only 3 laps. It sucked! Now I know what topic. Cold day at them heat up and I lowered they only went:
It was cold, tires to 30 like normal thinking the time. But if you can't recommends 42 front and went
well, i dont know. I'd still hate to recommend 42 for someone wanting to tear through sweepers out on public roads. contact patch is still too small, and heat up not enough. I run 36-38 because it DOES heat the tire up, give a bigger contact patch, AND increases it's own PSI to 40-42 ish depending on conditions. I personally feel that people that DON't ride hard enough would benefit from lower pressure. It would heat and stick more for them. To me, feel is mostly the suspension. They might be just like me: buy a busa, go home and read the manual, fill those tires up to 42 cuz it says so, and then watch Rossi in motoGP and think the engineers have designed my bike to ride like that as is.
This thread was about experiementing with LACK of heat up on a cold TRACK, and what I discovered, and it scared me enough to exit after a couple laps to see what was wrong. As mentioned, track PSI should NOT be run on streets for the reasons listed already.
On my very first track day, I lowered my PSI a whopping 3 lbs or so thinking that was fine for a non race street bike. THEN I started asking around, "Hey how do those good, fast guys rail on a corner with out sliding out? I'm sliding out of most turns on my bike?" first question out their mouth? "What tire pressure you running? OH NO NO NO NO NO YOu GOTTA lower it bigtime on the track!" Yes, they felt flat but the experienced guys assured me the feeling would grow on me and boy DID IT. Now I barely notice the slow, thick steering at the track, it just feels track-normal. I learned a bunch from much more experienced riders last couple years. One thing I learned is be flexible to crazy Ideas... 30 PSI? ARE YOU NUTS? Do you have any idea how much MY bike weighs? 30! Psshaw. right whatever. Now I'll never run higher than 32-34 on the track... too much slip
So, I apply some of that knowledge to the street where applicable and came up with 42 on long tours to reduce heat up, reduce wear and extend tire life, 30 at the track to max out heat up, increase wear and stickie, and FOR ME 36-38 on the street as a compromise tween race track railing and road hazzard compliance. If all the roads were track smooth? I'd run 30 all day long.
I'm running Metzeler M3's right now and if you check the tire makers website, here's what THEY recommend specifically for the Hayabusa - if you want to listen to the engineers:
SPORTEC M-1
Front 120/70ZR17M/CTL(58W)(P) SPOM-1 - 34 PSI - 3.5 INCHES
Rear 190/50ZR17M/CTL(73W)(P) SPOM-1 - 36 PSI - 6.0 INCHES
It's not really rocket science, and I bet you could easily run 32-42 on the street and be just fine.
I just feel at 42, you have an increased chance of sliding out of a corner when your buddie on the R1 starts railing some curves [see other recent threads]
MAN I type a lot! sorry
hey at least we are all discussing this and sharing ideas!
Now, maybe someday we'll decide which IS the very best tire! HA!
OK folks, the reason to run lower pressure at the RACE track (road course) is NOT to heat up your tires more
It is because the speed, braking, and cornering forces of running the track WILL HEAT
UP YOUR TIRES....thus increasing pressure
If you were to run 42psi at the track your tires will have a smaller contact patch than they will
have at 30psi...once you get your tires up to temp, your pressure will have increased
about 5 or 6psi. At 42 on the track the tires get slippery when they heat up and they slide
BIG TIME=NO GRIP
At 30psi when they heat up you are now @ 35-36psi...the tire is more flexible with a LARGER
contact patch=MORE GRIP
It is because the speed, braking, and cornering forces of running the track WILL HEAT
UP YOUR TIRES....thus increasing pressure
If you were to run 42psi at the track your tires will have a smaller contact patch than they will
have at 30psi...once you get your tires up to temp, your pressure will have increased
about 5 or 6psi. At 42 on the track the tires get slippery when they heat up and they slide
BIG TIME=NO GRIP
At 30psi when they heat up you are now @ 35-36psi...the tire is more flexible with a LARGER
contact patch=MORE GRIP
Now Nitrogen
The most important reasons to use it are:
1. You won't loose as much air pressure...it doesn't leak out as fast.
2. It doesn't increase as much when it gets hot(less fluctuation between cold/hot)...you can run a pound or two more.
3. It doesn't have the moisture that compressed air has.
4. The Ozone in compressed air over time is harmfull to tires...the tire stays softer, doesn't dry out as fast with Nitrogen.
The most important reasons to use it are:
1. You won't loose as much air pressure...it doesn't leak out as fast.
2. It doesn't increase as much when it gets hot(less fluctuation between cold/hot)...you can run a pound or two more.
3. It doesn't have the moisture that compressed air has.
4. The Ozone in compressed air over time is harmfull to tires...the tire stays softer, doesn't dry out as fast with Nitrogen.
agreed ..but you are a experienced track rider.a lets do a track day noobie, or a i read this on the org street guy trying it .is better not dropping the pressure.he will wash out with the low pressure rather than slide out with the high .lol(BA BUSA @ Oct. 05 2006,18:21) OK folks, the reason to run lower pressure at the RACE track (road course) is NOT to heat up your tires more
It is because the speed, braking, and cornering forces of running the track WILL HEAT
UP YOUR TIRES....thus increasing pressure
If you were to run 42psi at the track your tires will have a smaller contact patch than they will
have at 30psi...once you get your tires up to temp, your pressure will have increased
about 5 or 6psi. At 42 on the track the tires get slippery when they heat up and they slide
BIG TIME=NO GRIP
At 30psi when they heat up you are now @ 35-36psi...the tire is more flexible with a LARGER
contact patch=MORE GRIP
I learned DAY ONE at the track to run 31 front and 30 rear...then keep a eye on them
and adjust accordingly
You can't run those pressures on the street
40-42 is fine for street riding...if you like
to ride the twisties HARD...you will be better off dropping to 38-40, after you try that
for a while...you can drop it some more. You will know when you are too low on the pressure.
I usually run 36 f/r...if I'm gonna do a lot of freeway, I will
bump it up to 38-40
and adjust accordingly
You can't run those pressures on the street
to ride the twisties HARD...you will be better off dropping to 38-40, after you try that
for a while...you can drop it some more. You will know when you are too low on the pressure.
I usually run 36 f/r...if I'm gonna do a lot of freeway, I will
bump it up to 38-40
All of you bring up some very good points.
From my track experiences: I agree with WWJD.
Feel IS A SUPSENSION THING (as well as a steering damper thing if you have an adjustable one).
Tires are for GRIP. Contact patch. Tires in a sense can be associated with suspension b/c depending on grip levels remaining on a tire the suspension has to react and recover according to tire feedback.
With that said, feel and performance is improved by Suspension: getting the preloads adjusted to sag/weight. Then according to the track, adjust the compression and rebound. Every track will be different so every comp/reb setting will change by a few clicks, but usually not by much. Depending on what the tire is doing (heating up effieciently and adding pressure or not getting enough heat/pressure) you adjust suspension to compensate for proper feel and handling.
For me: track= 30-32 front (I like a slightly quicker steering) and 31 rear. That's with running sport/race groups or Intermediate/advanced level sessions. By the time I come into the pits and check the pressure, it's usually around 35f 34r and I leave it. Suspension adjustment is more important as the day goes on.
From my track experiences: I agree with WWJD.
Feel IS A SUPSENSION THING (as well as a steering damper thing if you have an adjustable one).
Tires are for GRIP. Contact patch. Tires in a sense can be associated with suspension b/c depending on grip levels remaining on a tire the suspension has to react and recover according to tire feedback.
With that said, feel and performance is improved by Suspension: getting the preloads adjusted to sag/weight. Then according to the track, adjust the compression and rebound. Every track will be different so every comp/reb setting will change by a few clicks, but usually not by much. Depending on what the tire is doing (heating up effieciently and adding pressure or not getting enough heat/pressure) you adjust suspension to compensate for proper feel and handling.
For me: track= 30-32 front (I like a slightly quicker steering) and 31 rear. That's with running sport/race groups or Intermediate/advanced level sessions. By the time I come into the pits and check the pressure, it's usually around 35f 34r and I leave it. Suspension adjustment is more important as the day goes on.
Wow talk about a cursed thread... one leaves and another comes to take his place.
Just something I found on the net after a quick search:
THE PRESSURE'S ON
Whatever tire you choose to run, be sure to set it to the correct pressure. And that information does not come from your owner's manual. Typically, tire pressures for the track will be much lower than you're used to. Ask the track-day organizers to find out the best setup. A cold tire pressure of 30 to 32 psi front and 28 to 30 psi rear is in the desired range. Always check the pressures at the start of the day, with cold tires.
Where did it come from?
SPORTRIDER.COM...You know the national magazine's website?
Im sure they did a little homework before they printed it.
LINK IF YOU WANT TO READ IT FOR YOURSELF
Seems that WWJD isnt crazy or stupid after all.
Just something I found on the net after a quick search:
THE PRESSURE'S ON
Whatever tire you choose to run, be sure to set it to the correct pressure. And that information does not come from your owner's manual. Typically, tire pressures for the track will be much lower than you're used to. Ask the track-day organizers to find out the best setup. A cold tire pressure of 30 to 32 psi front and 28 to 30 psi rear is in the desired range. Always check the pressures at the start of the day, with cold tires.
Where did it come from?
SPORTRIDER.COM...You know the national magazine's website?
Im sure they did a little homework before they printed it.
LINK IF YOU WANT TO READ IT FOR YOURSELF
Seems that WWJD isnt crazy or stupid after all.
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