Date:         Sun, 11 Mar 2012 08:01:45 -0700
Reply-To:     Don Hanson <dhanson928@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Don Hanson <dhanson928@GMAIL.COM>
Subject:      Re: Spark plug gap-Tire air!
In-Reply-To:  <4b90059f.3fb258.13601d0d68a.Webtop.48@charter.net>
Content-Type: text/plain; charset=ISO-8859-1

  From my records, filling race tires with nitrogen reduced the inflated
pressure *increase* by almost 4psi on my racecar.  Doesn't sound very
significant, but it was. With atmospheric compressed air, I needed to start
track sessions about 7psi below what I wanted to see during a race...with
nitrogen, I could start out just 3psi below my target tire pressures.

 My car ran on Goodyear racing slicks, usually.  I found a source for
NASCAR race-tire takeoffs.    I used 17" x 12.5" (tread width) rubber
(equivalent to 350/35 or so) that were inflated to about 22-28psi when up
to racing temperatures.

  We kept very careful records of both tire pressures and tire tread
temperatures...an important racetrack proceedure. It was useful to pull
into the pit lane during practice sessions and get readings of the tire
pressure and also 3 temperature readings across the tread width of each
tire....this would give us an idea of which part of which tire was
supplying the most grip (traction) and allow us (me, I had no real "crew")
to adjust the suspension for best performance.

  My tires took a couple of laps (on a ~2 min./lap track)  at race speeds
to "come up to temperature" which was typically around 220-300f at the
tires surface, as measured with the tire probe tool.  An over-inflated tire
ended up with tread readings very high in the center and cooler on the
edges...an under-inflated tire heated up very quickly,then got too hot and
very slippery.  Of course this is an oversimplification.

 The general idea of using nitrogen to inflate the tires was to be able to
begin each race with tires that were much closer to the optimum tire
pressure right from the starting flag without ending up with overinflated
tires after a few laps, or having to run 'under-inflated' for a few laps
till the temperatures and pressures came up.  The actual numbers I used,
from my race log books, show that when filling with just ambient air, I was
inflating my tires to a cold pressure of about 7psi less than they ended up
after attaining race temperatures and pressures.  When I used Nitrogen to
fill the tires, I could fill them to just 3lbs under my optimum pressure...

   This meant, when racing, that the first few laps when the field was all
bunched-up and there were large gains to be made over multiple cars that
having the best available traction (properly inflated tires) was a huge
advantage.

   During 'test-days' when we would sometimes use old tires inflated with
just air, I would often bleed off around 7psi of pressure after a few
laps....come in to the pit lane and get out with my gauge and find my tires
very over-inflated, with my temperature probe, the center of the tread was
much too hot (compared to the shoulders of the tread)

   I used nitrogen obtained from a welding supply in those 'welders
cylinders'.   One cylinder (about 4' tall) would last me perhaps 20-30 full
tire changes...I used a simple pressure regulating valve on the gas
'bottle' and a normal hose with a tire chuck that snapped on with a tool
air fitting.    For those who don't have room in the garage for a real air
compressor, a nitrogen bottle and a hose might be a good alternative to
going to the gas station and trying to get proper inflation.  You can trade
the empty cylinders for full.  Inexpensive and convenient....  Some of the
wealthy lazy guys used to power their impact tools from nitrogen bottles
even.

  What's all this have to do with Vanagon's tires?  Probably not too much,
since racing a Vanagon is unlikely.  The phenomenon of air pressure
changing as the tires heat up though, that is certainly very real!  If you
are truly obsessive (anal?) about having everything *just right* with your
vanagon....nitrogen filled tires are something you could do.   If you need
a convenient source of inflating, a compressed cylinder of nitrogen could
be kept around for your tire needs.

  Don Hanson

On Sun, Mar 11, 2012 at 5:52 AM, Mike B. <mbucchino@charter.net> wrote:

> Tire Rack says it best;
>
> http://www.tirerack.com/tires/**tiretech/techpage.jsp?techid=**191<http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=191>
>
> Mike B.
>
>
> On Sat, Mar 10, 2012 at 2:12 PM, Dave Mcneely wrote:
>
>  ask the tire shop personnel what the nitrogen does for the tire.  the
>> looks will amaze you.
>>
>> as most of us know, air is about 80% nitrogen.  most of us should be
>> checking and probably adding air to our tires no less often than
>> monthly.  I simply use a bicycle pump for my cars, and a small
>> electric compressor (the sort sold at auto supply stores to carry in
>> the vehicle) for my camper.  for shops to sell nitrogen is mostly a
>> scam.
>>
>> mcneely
>>
>> ---- Dennis Haynes <d23haynes57@hotmail.com> wrote:
>>
>>> Nitrogen for tires can be a good idea especially if the tire shop has
>>> oily or wet compressed air. Ask the tire shop if they do anything to
>>> ensure the oil from the compressor or the water from the compression
>>> process does not get into your tires. The looks will amaze you.
>>>
>>> Dennis
>>>
>>> -----Original Message-----
>>> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.**com<vanagon@gerry.vanagon.com>]
>>> On
>>> Behalf Of Dave Mcneely
>>> Sent: Friday, March 09, 2012 2:32 PM
>>> To: vanagon@GERRY.VANAGON.COM
>>> Subject: Re: Spark plug gap
>>>
>>> I think the next time a tire shop offers to fill my tires with
>>> nitrogen, I'll ask for some of that "seasonal air" instead.  think
>>> that'll get a reaction?  mcneely
>>>
>>> ---- Angus Gordon <birdworks@GMAIL.COM> wrote:
>>>
>>>> Thanks for the link George. I've been looking for one of these left
>>>> handed metric screwdrivers for some time now -
>>>>
>>>>
>>>> <http://kalecoauto.com/index.**php?main_page=product_info&**
>>>> cPath=5&produc<http://kalecoauto.com/index.php?main_page=product_info&cPath=5&produc>
>>>> ts_id=21>
>>>>
>>>>
>>>>
>>>> Angus
>>>>
>>>> www.wordless.me
>>>>
>>>>
>>>>
>>>> On Fri, Mar 9, 2012 at 8:19 AM, george jannini
>>>> <georgejoann@gmail.com> wrote:
>>>>
>>>>> Try these, no gap required:
>>>>>
>>>>>
>>>>> http://kalecoauto.com/index.**php?main_page=product_info&**
>>>>> cPath=2&produ;;cts_id<http://kalecoauto.com/index.php?main_page=product_info&cPath=2&produ>
>>>>> =5
>>>>>
>>>>
>>> --
>>> DavidMcNeelyy
>>>
>>>
>> --
>> DavidMcNeelyy
>>
>