Tire mounters offer nitrogen. Should I?

[RussMcB]

I stopped at a local tire store to see about mounting & balancing race tires. They said $15 apiece, that they like to give racers a break. (Doesn't sound all that great to me, but ...)

Anyway, they offered to fill the tires with nitrogen. I'm aware of the benefits, but hesitant because then I'd have one set that may not use the same cold starting pressures I normally use.

What do you think? Go for the nitrogen or stick with regular compressed air?

The tires are Hoosier bias ply slicks.

TIA.

[Charles Warner]

Russ,

Either will work just as well. If you opt for the NO then all tires should be filled the same and you then have to carry an NO bottle with you to the track (most of us do anyway) just to top off the tires when needed, or change to a new set, etc. Is it worth the hassle?

[Purple Frog]

The use of nitrogen or dried compressed air all all good things. BUT, only if done correctly.

The biggest gain for using nitrogen or compressed air is that you are not putting moisture into the tire. Moisture can cause serious radical tire pressure swings when it gets heated. We 'purge' the tires sometimes 8 to 10 times with nitrogen or dry air before we finally fill them. This helps flush out the moisture.

I'm not sure your neighborhood tire dealer is going to let you flush the tires 10 times with his nitrogen.

All is lost in the nitrogen deal if the tire installer uses excessive soapy water to mount the tire leaving excess inside. Probably the most important single thing to control in mounting the tires is that lubricant. And that is hard to do unless you stand by the installer and be a PIA.

If the inside of the tire is dry you have jumped the biggest single hurdle. Then it's your choice whether to run dry compressed air or nitrogen. It's just a case of testing to collect the data points to know how each will react. I like nitrogen, especially if Sean is offering it free.

Most of us prefer nitrogen mainly because it is dry. Many of the drier devices for compressed air are not as perfect as bottled nitrogen in getting a moisture free environment inside the tire. Nitrogen has different expansion properties than compressed air, thats where testing and data collection come into play.

But all is bunk if you don't get the original moisture out of the tire from the mounting process and original fill.


OBTW, the standard charge to "non-factory" drivers at the track for mounting and balancing 4 tires by GY or Hoosier seems to be running $55 to $60 . If inclined you can do it yourself. Dave and I changed out four tires and balanced in about an hour in the paddock one evening at the Runoffs. All the tools he used could fit in a attache case. Much smaller than the normal Harbor Freight setup. Pretty interesting experience.

[Stan Clayton]

Dave and I changed out four tires and balanced in about an hour in the paddock one evening at the Runoffs. All the tools he used could fit in a attache case. Much smaller than the normal Harbor Freight setup. Pretty interesting experience.

Meh, I'm waving the BS flag on this one...

It took Dave and I 20minutes (and two beers!) just to balance one tire!

[TimW]

OBTW, the standard charge to "non-factory" drivers at the track for mounting and balancing 4 tires by GY or Hoosier seems to be running $55 to $60 .

So, what exactly was the going rate at the runoffs after all? Was the surcharge steep for the privilege of having them done there?

Tim

[EYERACE]

yo your frogness...........interesting point about how wet was the inside when mounted.....i've generally taken the tire from the track dealer....who probably had a well working drier in their line.......and maybe 15 minutes later, let all their air out, filled with NO to about 22 pounds, let all that out and then filled with NO a second time to a little over what i'll want when i go out on track and consider it done. you make me think the trick might be to get the unwanted humidity from the mount out by doing my second purge when the tire comes in hot off the track the first time, wait not too long, let all that NO out and fill a second time. or maybe keep to the same idea of a second fill but do the third when hot. i think the thing is to not just fill and empty and fill and empty quickly right after mounting but give the unwanted water a chance to vaporize into whatever gasious material is inside the tire and then empty.

[TedV]

Meh, I'm waving the BS flag on this one...

It took Dave and I 20minutes (and two beers!) just to balance one tire!

that's cause y'all kept putting the beer on the tire, using it as a table

formula tires with the right kind of rims are easy to do. Hardest part is busting the bead loose. Some forumla tires can be put on without lube. Another point of moisture is just the atmosperic air in the tire before you even start to inflate it. What's the humidity in the south? I've seen some vacuum setups and also the purge method used.

::edit:: had my street tires flipped this morning, posted $15 per mount and balance, bout the same as at the track. you should hear the horror stories of local shops and race tires. Be sure they know what they are doing before they screw up your rims and tires

[Stan Clayton]

You guys really put nitrous oxide (NO) in your tires? Doesn't that make it kind'a tough to route it to the carb throat?

[EYERACE]

good point - the chemist would call it perhaps N and indeed not NO- the pressure container is painted orange as an industry standard i believe

[John Robinson II]

Stan,
You should keep replacing the air untill you can not see a vapor mist from the expelling air. Sometimes it might be 1 or 2 times sometimes more. The biggest reason is it keeps tire pressure growth consistent. I would not accept the track tire guys air as "dry", even though they have a drier inline the dessicant might not be up to snuf. I have a venturi type device that you can attach to the valve stem and suck all the air out, works pretty good on the rears but the fronts like to pull off the rims. I have also used an ac vacuum pump with the same results. You get lots of funny looks when you head back from the tire guys with 4 tires that are square and drawn up on the rims.

Russ,
I would be more concerned with how the corner tire guys machine clamps the rims. I only tried it once, after seeing how it tore up the inside of the rim I would not let them do the other 3. YMMV.

John

[RacerDave51]

I believe the molecular formula is N2. If I'm not mistaken what I use is a mixture of nitrogen & oxygen. I guess if the Oxygen is dry it won't matter all that much.

[Brian]

Is there a portable bead breaker that you can easily take with you to the track?

Brian

[-pru-]

I believe the molecular formula is N2. If I'm not mistaken what I use is a mixture of nitrogen & oxygen. I guess if the Oxygen is dry it won't matter all that much.

Yes, "common" symbol for Nirtogen is N2. Here is the Nirtogen (N2) description from Airgas:

http://www.airgas.com/browse/product...Field=Category

Nitrogen (N2) is a colorless, ordorless, nonflammable or a colorless, odorless, nonflammable cryogenic gas. Airgas offers unique BIP ® technology in argon, helium and nitrogen. BIP technology (an Air Products innovation) provides premium-grade purity at costs you would expect to pay for zero-grade gas using a purifier built into the cylinder.

[mark defer]

actually if the tire dealer has one of the newer model nitrogen generators, it will have a purge function which evacuates the tire before refilling with nitrogen. that eliminates the need for the fill/purge/fill procedure you refer to. at st clair, we run nitrogen religiously. that being said, i still feel that for everyday passenger tires, it's a bit of overkill. the industry has been pushing nitrogen fills as an add on money maker. the main feature/benefit promoted isn't the lack of moisture in nitrogen, it's that the nitrogen molecules are larger and the tire will experience less pressure loss that regular air. some retailers are doing such a good job selling it that people think that it's some magic elixer that will increase tire life and gas mileage over the use of air, but the truth is that if they just check the regular air in their tires once a month and keep the pressures up, there really is no added benefit. hell, most people don't even realize that plain old air is already 78% nitrogen. additionally, if they get a nitrogen fill, and add regular air to top it off at some point, they will probably drop from 100% to less than 90% nitrogen at which point they have negated any advantage over regular air. needless to say, i haven't put a nitrogen generator in my store yet. i believe i have lost 1 tire sale because we didn't have nitrogen and that customer was convinced they needed it. if that happens more often, i might need to bite the bullet and get one. btw, we do keep a cylinder of nitrogen around for the race tires we do.

mark d

[Mark H]

What Mark said.
I wonder if the N generaters are putting 100% N in the tire anyway? VS using a big green tank of pure N from Airgas? (like you should on a race car anyhow)
Using N on street cars IS overkill besides, unless they are changing their filters and driers in those shops all your paying for are the green caps!

PS John most of us here in Marietta have been using a tire shop that is owned by a drag racer and mounts all of Reese Cox's $$ Corvette tires. The big problem from using a Firestone type place isen't the rim clamps but the crappy balance job they do. Shoot half the time Hoosire balances my tires @ the track I have to move the weights so they won't hit the brakes??? But I do LOVE the purple tape.

[Charles Warner]

It's ALL overkill. If any of us can really tell the difference made by .5 psi or even 1 psi . . . . or especially the "rate" at which the tire grows . . . .

Figure out the growth factor using standard everyday air and live with it. If you really have to go the exotic route then hire Nigel Stepney - I understand he's between assignments at the present time.

[mark defer]

hey mark,
i resemble that remark.
I AM a "firestone type" tire store.

mark d

[Brian]

I sometimes take tires down to my local Tirecraft store in Dundas where I live. They have a machine that doesn't clamp on the rim nor actually touch the rim when mounting or demounting a tire. It can even do a 10" Mini rim. They sometimes can't get the wheel on the balancer right, though. The good news is since I buy all of my street tires from them and they know me, they do the race tires for free even though they don't sell me the tires!

Even so I usually do FFord tires at home with by HF machine and bubble balancer.

Brian

[Alan R Guibord]

The ADSA/WRIGHT team uses a mixture of half New Hampshire air and half New York. We find that the NY air is hotter than the NH air

[ghoneycutt]

I imagine many of you use this type stuff-
I have had good luck with this home set-up and have taken it to the track.
Hoosiers are harder to get on and off, (Leaving the tires in the sun soaked driveway helps), Goodyears are tougher to seat the bead due to softer sidewalls

I need to make a weighted flange for the balancer because the lightest tires on my lightest front wheels don't always compress the springs all the way. That said, I've saved a ton of $, can flip tires when needed and never had a balance problem. The last time I had a service station do my tires, they cracked the inner shell on my Panasport C4 rear and charged me $48.

[Mark H]

No Mark your a Defer type tire store. aka family owned.
Down here all Firestones well 95% are owned by American Tire (BFS) and the tech's are well lets say up to speed when it comes to doing a good static balance? I know I worked foe them for 8 yrs.

Our car was 4 lbs light last race so we had to add a pound to each tire to make weight??!@#$%&^ Air not N?

[John Robinson II]

Our car was 4 lbs light last race so we had to add a pound to each tire to make weight??!@#$%&^ Air not N?

Mark, You should try this in your shocks!!!

John

[Jon Horgas]

It's ALL overkill. If any of us can really tell the difference made by .5 psi or even 1 psi . . . . or especially the "rate" at which the tire grows . . . .

Figure out the growth factor using standard everyday air and live with it. If you really have to go the exotic route then hire Nigel Stepney - I understand he's between assignments at the present time.

Charles, no disrespect intended, but there is nothing exotic about it. It is not the tire growth itself that this is for, it is for the pressure. Yes, it does make a huge difference for a 1/2 or, God forbid, a full pound of air in the tire pressure gain. You will loose grip as the tire pressure, and it's spring rate, rises. The air pressure gain inside the tire creates the stiffness of the sidewall , and also changes the slip angle of the tire, changing handling and car setup. If you are consistant, it will show on your lap timer in a heartbeat.

Anyway, I would rather have Dave W. in my arsenal than Step.

[stephen wilson]

Has anyone used the preset tire "relief" valves to control your hot pressures? The only problem is they appear to require another hole in the rim?

[Purple Frog]

We've discussed them in the past. And then again in a bench racing session at the Runoffs.

Two potential problems:
1. Another potential point of failure.
2. We vary tire pressures from session to session, depending on temp., track temp., tire compound, and thickness of remaining tread.

Since we are teasing Charles. There are drivers such as DaveW, that do 'feel' 1/2 of psi. I think Dave might even be sensitive to 1/4 psi, he just won't admit it to me. I have had Dave come in during a test session and fiddle with 1/2 lb. At this years Runoffs we altered cold pressures quite a bit, some times to alter hot pressures.

That said, auto-regulators may be the cat's meow for some club racers.

[Charles Warner]

Charles, no disrespect intended, but there is nothing exotic about it. It is not the tire growth itself that this is for, it is for the pressure. Yes, it does make a huge difference for a 1/2 or, God forbid, a full pound of air in the tire pressure gain. You will loose grip as the tire pressure, and it's spring rate, rises. The air pressure gain inside the tire creates the stiffness of the sidewall , and also changes the slip angle of the tire, changing handling and car setup. If you are consistant, it will show on your lap timer in a heartbeat.

Thanks for the lesson . . . If you are really worried about the "huge difference . . . for . . . God forbid . . . full pound . . . gain" then I'd have to assume you have matched your springs exactly (a 1% variance - less than touted by Hypercoil or Eibach - can easily lead to a 10# difference in individual rates), carefully replaced all rod ends to remove any stiction differences side to side, carefully had your shocks dynoed, matched the tires as to circumferences at given pressures, have levelled your alignment platform carefully ala Richard Pare's instructions, have a matched set of new sticker tires that is saved for alignment purposes only, have performed Richard's chassis stiffness test, have made sure your chassis is perfectly square, etc., etc., . . .

Yes, a change in air pressure will affect the sidewall stiffness and, IMHO more impotantly, changes the contact patch shape. I still posit that the vast majority of us can not tell the difference .5 psi delta makes and any "difference" felt or seen would be due to expectations from a change rather than the change itself. (Sort of like the guy who changed his front bar from full soft to full hard and went two seconds a lap faster because of it . . . until he noticed the bar was not connected.) A double blind test would be quite revealing. For our purposes and level of exactness using air or nitrogen matters little. Determine the pressures at which your tires work best as indicated by the tire temps across the tire and determine the starting pressures you need to achieve those results based on the day, track and tire compund. As far as Dave W., most of the things (if not all) I mentioned above have probably been done on the Citation so a small change as suggested may be more evident to him.

As for the pressure relief valves, I have had good luck with them when used and the may be adjusted very quickly in the pits within their range.

[steve zemke]

I don't have a dog in this fight, but I would be willing to bet Jon Horgas did nine of the ten items Mr. Warner asked about. There are people in this game that at exact, and then there is Jon. He is as exacting as his company's name.

[Charles Warner]

Steve,

No fight here. I'll say again - a double blind test would be revealing.

I'm not saying a driver can not be sensitive to small changes. Several years ago Mario Andretti got in Duncan's 1979 Lotus F1 for a few laps at the Glen. The car had been generally set up but not for racing. After a few laps Mario came in and asked for a couple of turns in one spring and another small change somehwere else. He went back out and came in and said "that's it." When they got the car back to the shop they put it on the scales and it was within a few pounds of being perfect. And he hadn't driven that car or one like it in years. So, some drivers can notice subtle changes. My point is that most of us can not.

For the crewchiefs out there - test your driver. Let him do a few laps, bring him in, and make a change to the tire pressures - up a pound, down a pound or nothing at all. Don't tell him what you did. Send him back out and, after he comes back in ask him what you did.