Re: Tire pressure
 

Mark:

If you aired up to 28lbs after a day's wheelin', then the tires weren't
"cold."

"Cold" means not having been driven for at least a few hours.

Tom

"Mark" <axolotl73@hotmail.com> wrote in message
news:1161922204.827204.192760@m7g2000cwm.googlegro ups.com...
>
> billy ray wrote:
> > Air pressure in a tire is directly proportional to temperature. In the
> > absence of other forces, you will gain or lose about 1 psi for every 10
> > degrees (F) temperature change.
>
> I was a little surprised by that effect. Aired up to 28psi after a
> day's wheelin', temps in the high eighties. Drove home (same
> elevation) and the next morning (60s) they were all @ 23psi.
>

Re: Tire pressure
 

According to Billy Ray, (and I believe he is correct) you will lose about
1psi for every 10 degrees of temperature change.

Tom

"DaveW" <spsffan@verizon.net> wrote in message
news:dKf0h.11010$LA.4573@trnddc06...
> Yeah, but I always wondered about places like the high desert where
> daytime can be 100 and nights can be 60. It would seem that the
> differential between these extremes could cause a tire that was inflated
> to proper pressure at 5 AM to be seriously overinflated by 4 PM.
>
> Any thoughts?
>
> DAve
>
> mabar wrote:
> > And "cold does not mean cold daytime temperatures. "Cold" means not
having
> > been driven for at least a few hours. For example: you could check your
> > tires when "cold" on a 95 degree Florida day.
> >
> > Tom

Re: Tire pressure
 

According to Billy Ray, (and I believe he is correct) you will lose about
1psi for every 10 degrees of temperature change.

Tom

"DaveW" <spsffan@verizon.net> wrote in message
news:dKf0h.11010$LA.4573@trnddc06...
> Yeah, but I always wondered about places like the high desert where
> daytime can be 100 and nights can be 60. It would seem that the
> differential between these extremes could cause a tire that was inflated
> to proper pressure at 5 AM to be seriously overinflated by 4 PM.
>
> Any thoughts?
>
> DAve
>
> mabar wrote:
> > And "cold does not mean cold daytime temperatures. "Cold" means not
having
> > been driven for at least a few hours. For example: you could check your
> > tires when "cold" on a 95 degree Florida day.
> >
> > Tom

Re: Tire pressure
 

According to Billy Ray, (and I believe he is correct) you will lose about
1psi for every 10 degrees of temperature change.

Tom

"DaveW" <spsffan@verizon.net> wrote in message
news:dKf0h.11010$LA.4573@trnddc06...
> Yeah, but I always wondered about places like the high desert where
> daytime can be 100 and nights can be 60. It would seem that the
> differential between these extremes could cause a tire that was inflated
> to proper pressure at 5 AM to be seriously overinflated by 4 PM.
>
> Any thoughts?
>
> DAve
>
> mabar wrote:
> > And "cold does not mean cold daytime temperatures. "Cold" means not
having
> > been driven for at least a few hours. For example: you could check your
> > tires when "cold" on a 95 degree Florida day.
> >
> > Tom

Re: Tire pressure
 

Grumman-581 proclaimed:

> "DaveW" <spsffan@verizon.net> wrote in message
> news:dKf0h.11010$LA.4573@trnddc06...
>
>>Yeah, but I always wondered about places like the high desert where
>>daytime can be 100 and nights can be 60. It would seem that the
>>differential between these extremes could cause a tire that was inflated
>>to proper pressure at 5 AM to be seriously overinflated by 4 PM.
>>
>>Any thoughts?
>
>
> Lookup Boyle's Law... Just remember though that the temperature is
> referenced in degrees Kelvin, not Celsius or Fahrenheit... 100F = 38C =
> 311K... 60F = 16C = 289K... Thus you will have a (311-289)/289 percent
> difference (i.e. 7.6%)... If your pressure is at 30psi at 60F, it will be at
> 32.3psi at 100F... Of course, in this example, I'm assuming that volume
> remains constant, but since we're talking about a rubber tire, that's not
> exactly true, but it would only add a small change to the result and it
> would be a reduction in the percentage anyway...
>
> Yeah, I know that Boyle's Law refers to *ideal* gases and that air is not
> one, but it's close enough for what we're talking about here...
>
>
And at highway speeds, the difference between desert and normal area is
pretty much mooted, particularly if slightly underinflated.

Re: Tire pressure
 

Grumman-581 proclaimed:

> "DaveW" <spsffan@verizon.net> wrote in message
> news:dKf0h.11010$LA.4573@trnddc06...
>
>>Yeah, but I always wondered about places like the high desert where
>>daytime can be 100 and nights can be 60. It would seem that the
>>differential between these extremes could cause a tire that was inflated
>>to proper pressure at 5 AM to be seriously overinflated by 4 PM.
>>
>>Any thoughts?
>
>
> Lookup Boyle's Law... Just remember though that the temperature is
> referenced in degrees Kelvin, not Celsius or Fahrenheit... 100F = 38C =
> 311K... 60F = 16C = 289K... Thus you will have a (311-289)/289 percent
> difference (i.e. 7.6%)... If your pressure is at 30psi at 60F, it will be at
> 32.3psi at 100F... Of course, in this example, I'm assuming that volume
> remains constant, but since we're talking about a rubber tire, that's not
> exactly true, but it would only add a small change to the result and it
> would be a reduction in the percentage anyway...
>
> Yeah, I know that Boyle's Law refers to *ideal* gases and that air is not
> one, but it's close enough for what we're talking about here...
>
>
And at highway speeds, the difference between desert and normal area is
pretty much mooted, particularly if slightly underinflated.

Re: Tire pressure
 

Grumman-581 proclaimed:

> "DaveW" <spsffan@verizon.net> wrote in message
> news:dKf0h.11010$LA.4573@trnddc06...
>
>>Yeah, but I always wondered about places like the high desert where
>>daytime can be 100 and nights can be 60. It would seem that the
>>differential between these extremes could cause a tire that was inflated
>>to proper pressure at 5 AM to be seriously overinflated by 4 PM.
>>
>>Any thoughts?
>
>
> Lookup Boyle's Law... Just remember though that the temperature is
> referenced in degrees Kelvin, not Celsius or Fahrenheit... 100F = 38C =
> 311K... 60F = 16C = 289K... Thus you will have a (311-289)/289 percent
> difference (i.e. 7.6%)... If your pressure is at 30psi at 60F, it will be at
> 32.3psi at 100F... Of course, in this example, I'm assuming that volume
> remains constant, but since we're talking about a rubber tire, that's not
> exactly true, but it would only add a small change to the result and it
> would be a reduction in the percentage anyway...
>
> Yeah, I know that Boyle's Law refers to *ideal* gases and that air is not
> one, but it's close enough for what we're talking about here...
>
>
And at highway speeds, the difference between desert and normal area is
pretty much mooted, particularly if slightly underinflated.