"Period Correct" Racing Tyres

[Gus Meyjes]

What is amazing about Nitro is that you don't loose pressure near as fast as with air. I put it in my Vredesteins 3 years ago and the pressure is still the same!
   
   Gus

[aex125]

For an impartial study of the leak rates of Nitrogen vs Air in tires, have a look at the link below. I have not seen anything similar for pressure stabilization, so am not sure about those claims.
   
   http://news.consumerreports.org/cars/2007/10/tires-nitrogen-.html
   
   Jay

[AcecaRacer]

The purpose of using Nitrogen is not about leakage.  At least for racing purposes where the tires are subjected to strong heat fluctuations in a short period of time, Nitrogen has a much lower vapor content and thus is much less succeptable to pressure changes.  Period.  When your tire pressure changes as much as 1/2 PSI, your handling can change at the edges, not good.

[Gus Meyjes]

I know that's not the purpose, but it is an added benefit for rad use...
   The findings in Consumer's reports being what they may, clearly I did not have that result. Maybe Vredestein produces a tighter tire!

[3.8Jaguar]

Nitrogen filling is a great way of limiting fluctuations in pressure due to temperature changes but first you still have to get your running pressures correct to optimise contact patch and maintain as steady temperature range once up to racing loads as much as possible.
   
   If your running temperature is to High the tyres will go off and the coefficient of friction between tyre and track will diminish. High temperatures can be caused by a number of factors such as , High track temperature, incorrect compound for track or configuration of vehicle , incorrect tyre section/profile for configuration of car etc etc. The most common cause for historic cars though is to low a pressure which results in the tyre working too much. Imagine trying to snap a plastic ruler, you keep on working the rule in one spot until the polymer at the point of stress reaches a temperature where it becomes soft and the fails, its the same for the polymers in tyres.
   If your tyres are maintaining a temperature of around 85 degrees C this is roughly the right running temperature around 110 and above and the tyre is over heating and you are loosing grip.
   
   I hope this is of help
   
   www.bristolengineering.co.uk

[aex125]

quote:Originally posted by Gus Meyjes
   
I know that's not the purpose, but it is an added benefit for rad use...
   The findings in Consumer's reports being what they may, clearly I did not have that result. Maybe Vredestein produces a tighter tire!
   
   
   

   Gus,
   I had read that report many years ago shortly after the test was done and decided to check N purity levels that are being used now. It looks like the N levels being used now are higher and so maybe your tire dealer uses a much higher purity N than the 95% from th original test.
   
   Acecaracer,
   If water vapor causes the fluctuations, could you use dried air and get the same results?
   Jay

[AcecaRacer]

Ran 32F 34R and the car was better than ever.  Literally transformed how she handles.  Now will tweak and fine tune the best pressures, but clearly north of 30 is where these tyres/tires are happiest.
   
   Thanks for the great advice.

[shep]

I was just reading through some of the old posts and saw this one again. I am glad the 32-34psi worked for you too. Sadly Ian Moss who shared his tyre information with me, passed away earlier this year. It is nice to know his advice will live on, both sides of the pond. This year I am lucky to have been asked to drive John Able's 1959 Daimler SP250 (Dart) at the Goodwood Revival. It was successfully campaigned in the USA by Duncan Black in period, and John has put together a website on the car (racing-sp250.co.uk/Duncan-Black.html) As he points out Duncan was the son of Duncan Black snr who founded Black and Decker power tools. More fun with tyre pressures!