Author Topic: More tire info......maybe.  (Read 2802 times)

Offline niles500

  • Niles500
  • Hero Member
  • *****
  • Posts: 1317
  • ROSIE
Re: More tire info......maybe.
« Reply #15 on: July 27, 2007, 09:20:49 AM »
I agree Prather - "hot inflation" pressure would be dependent on multiple variables including ambient temp, road surface temp, % of water vapor in tire, speed of vehicle, and the amount of force or friction being applied to the tire. I've never done the test but I have heard up to 10% pressure increase is normal for summer at highway speeds.

Consider this ;

Your leaving Fairbanks, AK in the winter and heading to Brownsville, TX - Before you leave you fill your tires per 'cold inflation' instructions to 100 psi (air or nitrogen - take your pick) - you then drive to Brownsville - what do you suppose your 'cold inflation' is now? - Now think about the return trip - Not to mention that the air gets thinner as your longitude or elevation goes higher - that's why I just keep my tire at the highest psi for the load and check them often - I don't like it when safety equipment is marketed as 'maintenance free' because it really isn't - there are many things other than leaking oxygen that will cause your tires to underinflate and only the constant physical inspection and pressure testing of each tire will ensure safe operation - FWIW
(\__/)
(='.'=)
(")_(")  

- Niles

Offline niles500

  • Niles500
  • Hero Member
  • *****
  • Posts: 1317
  • ROSIE
Re: More tire info......maybe.
« Reply #16 on: July 27, 2007, 10:10:53 AM »
In addition - for the scientific types - the relative molecular mass (0 degrees centigrade/1 atmosphere) of Nitrogen= 28 and Oxygen= 32 - and a Diffusion coefficient (mm sq.) of Nitrogen= 17.5 and Oxygen= 17.5

At different temps and/or pressures the diffusion rates will vary -
(\__/)
(='.'=)
(")_(")  

- Niles