[Spridgets] Air Pressure & Lug Nut Torque

[bmwwxman]

So what are the variables in this equation for tire pressure?

1.  Ambient temperature - which is constantly changing (I'm a meteorologist)
              I seriously doubt after about a minute of driving that the
ambient temperature
              will be a significant contributor to tire temperature and
pressure
2.  Friction - tire on the road (or track) surface
               Also probably a very small contribution until......
3.  Tire construction - flex of the sidewalls going through turns
               Clearly a more significant contribution to tire temperature.
Watch the F-1
               and Indy car boys swerving to build up tire heat.
4.  Finally, the tire compound itself - its ability to hold heat once it
has been heated.

The warmer a tire gets, the warmer the air in it gets and the higher the
pressure in
that air. Simple physics.

I would think that all of these factors enter the equation but to what
extent I do not know.
The racers will have a better read on this methinks....

On Tue, Aug 28, 2018 at 12:37 PM Ron Soave via Spridgets <
spridgets at autox.team.net> wrote:

> What you ultimately care about is the contact patch and tread behavior at
> temperature. It depends on the tire, not the car. The manufacturer should
> list that somewhere on their website.
>
> Ron Soave
>
> On Aug 28, 2018, at 7:39 AM, Rick Fisk via Spridgets <
> spridgets at autox.team.net> wrote:
>
> Allen,
>
> Not wanting to start anything here, but your tire pressure recommendations
> don't make sense to me.  I've never seen the recommended tire pressure is
> at 32 degrees F spec in a manual anywhere.  ???  Seems to me the tire
> pressure should be the same no matter what the temperature is.
>
> For every 10 degree F rise in air temperature the pressure in your tires
> will rise about 1 psi and fall 1 psi for every 10 degree drop in
> temperature.  So to maintain the car manufacturer's recommended tire
> pressure you should reduce the pressure when the temp goes up and raise it
> when the temp drops.
>
> Why would you always add 5 psi to the recommended pressure?  Seems to me
> the car manufacturer probably knows best when it comes to recommended tire
> pressures for their cars.
>
> Rick
>
> Sent from my keyboard
>
> On Aug 27, 2018, at 10:39 AM, Allen Hefner via Spridgets <
> spridgets at autox.team.net> wrote:
>
> Don't forget that the recommended tire pressure in the manuals is at 32
> degrees. You usually add 1 PSI for every 10 degrees above freezing. Nobody
> seems to know that anymore. The manuals just say ## PSI cold. I always just
> add 5 PSI to the recommended pressure.
>
> Allen Hefner
> Norristown, PA
>
> *Current:*
> 2016 Subaru outback somewhere
> 2006 Chebbie
> *Former:*
> 1963 Sunbeam Alpine Series III
> 1967 Triumph TR4A IRS
> 1964 VW Type I
> 1967 VW Type II
> 1967 Rover 2000TC
> 1977 MG Midget (Sniff!)
>
>
> On Tue, Aug 21, 2018 at 1:40 PM John Farley via Spridgets <
> spridgets at autox.team.net> wrote:
>
>> I am running 175/70 R13s on my 1275+ Bugeye with front disc brakes.  What
>> are folk’s recommendations for tire air pressures & lug nut torque?
>> The manual  seems low for both.
>> Thanks,  John F.
>> ------------------------
>>
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-- 
-- 
Cheers!!
Jim Johnson
UHI Aviation Meteorology <https://www.facebook.com/MET105/?ref=bookmarks>
Adjunct Professor
E-Journal of Severe Storms Meteorology <http://www.ejssm.org/> - Chair

"Tact is the ability to tell someone to go to hell in such a way that they
look forward to the trip."
Winston Churchill
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