[Spridgets] Air Pressure & Lug Nut Torque

[Mike Rambour]

  I have to partially agree.  I also have never seen the 32 degree 
specification and that would seem near impossible for any owner or even 
tire shop to check the pressure at that point (maybe a few lucky ones in 
the cold part of the country for a few months).

  But Tire pressure is not the same when hot or cold, check your tire 
pressure in the morning before driving and then check it again after 
10-15 miles down the freeway and you will see it has increased.  In my 
new truck, I have tire pressure monitors, I will start at 35psi in the 
morning and average 39psi on the freeway. Its interesting to see that 
the front tires will get to 40psi and rears stay at 39psi, but when 
towing  a heavy trailer, the rears will get to 41-42psi while the fronts 
stay at 39.  And this is always starting at 35 cold, by cold I mean 
mid-60's ambient temperature and before driving at all.  I assume the 
difference in PSI is due to weight on the tire at the time, motor up 
front and 1-2psi then empty rear of truck, towing its the other way 
around, more weight on the rear.  And no, I do not use my TPM to set my 
tire pressure, I use a proper tire gauge, but the TPM is never more than 
1 psi off.

  Some people add PSI in the belief that they will get better mileage, 
doubt its true after a certain point.  Yes, if your tires are under 
pressured, then getting it to manufacturers specs will improve mileage 
(by what, a few tenths maybe, assuming the tires are not flat to begin 
with) but after you are in spec, I seriously doubt it will improve the 
mileage more than a tenth of a MPG.

     Mike


On 8/28/2018 5:39 AM, Rick Fisk via Spridgets 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 <mailto: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
>>
-- 
A gun is like a parachute, if you need one but don't have it,
you'll probably never need one again.

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