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Thread: Tire pressure & temperature drop Reply to Thread
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  Topic Review (Newest First)
02-27-2008 04:16 PM
ptcbob Moles?? Kelvin? Kelvin has some moles?? I thought this was about tar pressure. Ha Ha
Sorry!
Bob
02-27-2008 03:37 PM
mr_embrey
Quote:
Originally Posted by Dianna View Post
Ok, so you are saying you psssst'd out 2 lbs of air

(Sorry, couldn't resist!)
I Think I just psssst'd my pants!!
02-27-2008 01:20 PM
93VN750 Here is one source you can reference: http://www.drivegreen.com/Motorcycle...KAWASAKI.shtml

Jon
02-26-2008 05:24 PM
Knifemaker Most tire makers have a reccomended tire pressure that is figured for our bike...this can be hard to find sometimes.

If you still have stock tires, go by the owners manual. If you bought aftermarket tires for it..check the makers website for info..or post your question here as many here have tried various tires and may know the reccomended pressure.

The pressure on the tire itself is usualy the MAXIMUM PSI the tire can hold, and it not usualy the pressure you should fill them to.

KM
02-26-2008 03:39 PM
aradams
Quote:
Originally Posted by ruger View Post
factory spec of what?.....the tire factory spec the psi on the side of the tire or kaw's bike manual psi, factory spec for the bike? sometimes they're not the same. so which one to use?
if you have changed from oem tires, then you should use the tires for your guide, considering your riding style, load etc. imho
02-26-2008 02:54 PM
ruger
Quote:
Originally Posted by AJCruzin View Post
Your tire pressure should be set to factory spec (at a minimum depending on your weight and riding style) regardless of outside temp. It shouldalso always be checked when the tires are "cold" or have not been ridden on for a minimum of 3 - 4 hours (IIRC). Any rise in pressure from heat caused by riding is not relevant.
factory spec of what?.....the tire factory spec the psi on the side of the tire or kaw's bike manual psi, factory spec for the bike? sometimes they're not the same. so which one to use?
12-21-2007 03:55 PM
AJCruzin Your tire pressure should be set to factory spec (at a minimum depending on your weight and riding style) regardless of outside temp. It shouldalso always be checked when the tires are "cold" or have not been ridden on for a minimum of 3 - 4 hours (IIRC). Any rise in pressure from heat caused by riding is not relevant.
12-19-2007 06:46 PM
Scoop Just had a flat fixed on my car this mroning and, while waiting, I read a Michelin brochure about this. It had a rule of thumb stating the pressure in a tire will drop about 1 psi for every change in 10 degrees F.
12-19-2007 02:56 PM
Dianna
Quote:
Originally Posted by jonathanrsr View Post
gentlemen, for your replies. Curtis, thank you for your in-depth explanation. I check the pressure before every ride, and only recently have we had cold (30's) temps, and that's when I noticed the pressure drop.

niterider, good observation! I didn't pay much attention to the top of my valve stem cap until I noticed a 2 lb drop overnight. Turned out that as I was trying to get my tire guage on the valve stem, I loosened the threaded part of the valve stem, and the air leaked out. THAT's when I realized why the top of the valve cover was notched. DOH *G*
Ok, so you are saying you psssst'd out 2 lbs of air

(Sorry, couldn't resist!)
12-19-2007 10:36 AM
93VN750
Quote:
Originally Posted by curtis97322 View Post
I think the question is - if I filled the tires when it was 80 degrees out and want to ride when it's 40, do I have to adjust for the temperature difference?

Right?

While you should check your tire pressure before every ride, the pressure difference is negligable with the range of temperatures a sane person would ride in.
Quick chemistry lesson...

PV=NRT (T is in kelvins) - P is pressure, V is volume, N is number of molecules (in moles) and T is temperature in Kelvins. Simple algebra will change the formula to P=T/V

30 degrees farenheit = 272 kelvin
100 degrees farenheit = 310 kelvin

I don't feel like working the math, but at 32 psi that gives a pressure drop of about 4 psi (many gauges are only accurate to 2 or 3) and most people don't ride in that wide a temperature range.

All that to say - it's a good idea to check your tire pressure before each ride, but the change in pressure due to temperature is generally negligible. (and yes, the tires will heat up some during a ride making same difference even more negligible).

Ok... gotta run to work...
Using 100F @ 35psi, 10L for vol, .93 moles, calucating for 30F, all other variables remain the same yields 30.6 psi, that is a significant change, worth correcting.

Jon
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