Question about increased PSI while driving

[iklo]

One day the longer I draw the lower my PSI were. Up until it went into the 25 range. Also the temperature went down by 30 degrees. The only thing up was the elevation: 13345ft. Central Colorado it was. Strange.

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[azjl#3]

My guess they filled new tires with nitrogen.

 

[jeepingib]

I fill up with helium +20 extra mpg.

Hydrogen is where it's at. Even lighter!

 

[Twisted10]

i put more psi in my tires to save fuel. then i mash the throttle and wonder why i still get 6mpg.

 

[azwjowner]

Hydrogen is where it's at. Even lighter!

No, vacuum is even lighter. That would be a negative PSI because it's measured relative to outside pressure. Run negative 14.7 PSI for the lightest tires.

 

[aeonixx1001]

On my normal routes here in FL, I am used to seeing a 4 or 5 PSI increase in my tires while driving, per TPMS. However, last week I purchased new tires, the same size as the old ones, and the PSI, on the same roads, same speed and duration, I am only having a 1-2 PSI increase. The TPMS sensors were not replaced.

This baffles me, and I am curious why there is a difference. I went from a 35x12.50R17E Falken Wildpeak MT to the same size and load rated Toyo Open Country R/T Pro (a very new model, a hybrid MT). Any ideas?

Different materials, wall thickness and type. Lot of things. I guess LOL

 

[Ratbert]

Tires with nitrogen, the pressures do not increase or decrease. When I mean regarding the tires will grow, I mean the pressures do not increase.

All gases expand and contract with temperature. That's been an established principle in physics and chemistry that was discovered over the 17th to 19th centuries. The fundamental principle is called Ideal Gas Law.

Nitrogen isn't magic. It merely expands and contracts at a slightly different rate than "normal" air.

That slightly different rate might be relevant in racing or aircraft, but not here.

Hopefully I don't need to start quoting the relevant equations.

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