Tire pressure,.. cold vs hot

[DonRed7]

Just a interesting thing from my trip down MidSouthern US that i had always wondered about regarding temp rise vs' tire pressures,.....*totally unscientific*

1) Front tire pressure before leaving the motel one morning was 39 psi (it was a cool morning)

2) Pulled in for fuel about mid day after both excessive interstate traffic and blistering collector asphalt temperatures (i looked down once and the display and it read 40 dec Celcius,...You do the conversion to F).... Just for kicks i immediately after fueling up checked the front tire pressure and it was 41 psi,...The tire was very warm...And as mentioned i expected a larger diff, Anyhoooo

-Don

 

[snikr]

I guess that means you have your air pressure in your tires set just about right.

Tom

 

[Scab]

Somebody here (smarter than me, or course) once posted the mathematical formula for calculating the pressure change according to temperature. But, being me, I forget who posted it or what that formula is.

 

[panayoti]

PV=NRT

 

[Scab]

Geez, you coulda waited a little longer to make it look hard.

 

[Derek]

my pressure rises about 5psi consistently in both tires.

derek

 

[MCRIDER007]

Somebody here (smarter than me, or course) once posted the mathematical formula for calculating the pressure change according to temperature. But, being me, I forget who posted it or what that formula is.

Air volume (and air pressure) changes in direct proportion to its change from absolute zero which is -459.72 degrees F. In the real world, if you start from 80 degrees F, it would take a temperature change of 54 degrees to change the air pressure by 10 percent.

If you want to measure air pressure at highway speeds you need to take the measurement before the tire cools down. Taking a measurement 5-10 minutes after leaving the highway is going to understate the actual air pressure at highway speeds. My FJR, riding solo, normally runs 44 in the front and 46 in the rear at highway speeds.

 

[JimLor]

I did a little "experiment" with tire pressures a couple of months ago. And if I could find where I put my notebook so I wouldn't lose it I'd be able to give you specific results! But, from memory, using various pressures I found the average rise to be between 7 - 9%. I ran the front from 36 - 29 and the rear from 38 - 42 and found the results be be fairly consistent. Again, if I recall correctly, the rear actually had a higher percentage increase than the rear (~1% give or take). Don't know how that measures up to the formulas, etc, but that's my emperical data!

 

[blueman]

A few years ago one of my sons was trying to figure out how to lighten his yamaha YZ-250. I told him it was easy, all he had to was fill his tires with helium! He never asked me how much it would lighten his bike before he enbarked on a journey to find a pressurized helium container. I bet he thought he would be able to jump his bike higher. After a non productive search I could not help but tell him it would not lighten his bike. But he could impress his friends if he had Helium in his tires by sucking on them and talking funny!

 

[Bustanut joker]

Geez, you coulda waited a little longer to make it look hard.

Well ya know.....

I did this Lavitra thing an...

I feel for ya miz scab...

Hopefully it's not a lifelong affliction.

:jester:

 

[Scab]

She hopes otherwise...

 

[Rickster]

pv = nrt