distaff
Alberta
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Joined: 02/25/2008
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Does anyone use a TMPS in cold weather? I have pulled out when it was -20 and the tire pressures were consequencely very low. I didn't put any air in (when they say the cold recommended pressure they mean 60 degrees). When I got to really hot weather all my tires were 10 PSI over the targets. I see that Hawks Head claims to have a cold weather system.
http://www.tpms.ca/PTHDPLUS.html
Paul
2006 Beaver Patriot Thunder
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Jack M.
Calgary, Alberta, Canada
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Cold temperatures will fool a pressure gauge let alone a TPMS. Our Honda CRV factory system was displaying a fault when temperatures got below freezing, and the Doran Pressure Pro was reading quite low, to the point of 'alarming'. I made sure that all pressures, before travelling were at least even on each axle of the coach, and the same on the CRV. As we started heading south out of Alberta the increasing rolling temperatures became more normal. Now that we are in Yuma the pressures are about right. It is as much about having same pressures on an axle as it is the right pressure. I am considering increasing the Hydrogen from 78 percent to 100 percent as I understand that the pressures will be more stable, and some even profess a better ride.
Jack & Nim Myton
'07 Revolution LE, 40E, DSCVRY "Reveille"
`08 CR-V, `RVPUSHR`
Moderator, FMA Revolution Owners Group, Good Sam, FMCA
www.revolutionmotorhome@yahoogroups.com
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Gale Hawkins
Murray, KY
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Yes. That is a nice of the computerized TPMS. You can take off with the alarm sounding and watch them come back into spec soon after you get underway. If they do not then you know it is time to top off but with our TPMS that can be a year or so we find.
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sum1
So-Cal
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Joined: 11/07/2005
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distaff wrote:I didn't put any air in (when they say the cold recommended pressure they mean 60 degrees). I think that in this context, cold means the temperature before you start driving for a normal day with normal conditions. I've never seen a reference to "60 degrees". On the other hand, if we know we're going from one extreme to the other on a particular day, maybe we should stop and adjust. We just have to remember to keep it high if it hasn't sat and cooled. Our experience checking cold vs warm can guide us as to how high.
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wallynm
Los Alamos NM
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Joined: 09/27/2000
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TP vs Cold
You may want to read this.
distaff wrote:Does anyone use a TMPS in cold weather? I have pulled out when it was -20 and the tire pressures were consequencely very low. I didn't put any air in (when they say the cold recommended pressure they mean 60 degrees). When I got to really hot weather all my tires were 10 PSI over the targets. I see that Hawks Head claims to have a cold weather system.
http://www.tpms.ca/PTHDPLUS.html
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DeweyClawson
Enon Valley, PA
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Jackm wrote: I am considering increasing the Hydrogen from 78 percent
Can you say Hindenburg
Hopefullly you are joking
The fool learns from his own mistakes.
It is the wise man who learns from the mistakes of others.
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DeweyClawson
Enon Valley, PA
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JackM wrote:Cold temperatures will fool a pressure gauge let alone a TPMS
I don't think so. The gauge may be faulty, cheap etc. sticky. The gauge generally reads lower at lower temps because the press is lower. Temp and press are directly proportional. Double the temp, double the press. Remember, temp is measured from absolute zero,(kelvin scale) not the arbitrary freezing point of water. about minus 459F deg, minus 273C. So an increase of 30C deg is about a 10% increase so expect a 10% increase in press.
Start whith the correct press. When you get to a warmer clime, let the tires cool to ambient, hour or so, and adjust to correct press.
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DDinCincy
Cincy, OH
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DeweyClawson wrote:Temp and press are directly proportional. Double the temp, double the press.
Not too sure this is accurate. I frequently use the coach in the winter and if I set my tires to 120psi at 20 degrees, I've NEVER seen them increase to 240psi as the temp has climbed to 40 degrees.
Rather, each 10 degrees in temp. variation should cause a reciprocal change in pressure of about 1psi.
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DeweyClawson
Enon Valley, PA
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Did you take high school physics????
Read the rest of the post.
The temp change is based on the Kelvin scale, where zero is minus 459 deg F.
The mathematical equation for Boyle's law is: PV=k
where:
p denotes the pressure of the system.
V is the volume of the gas.
k is a constant value representative of the pressure and volume of the system, all at a constant temp.
Charles's law (also known as the law of volumes) is an experimental gas law which describes how gases tend to expand when heated.
It can be expressed as V1T1 = V2T2
Combine these two laws and you derive the modern ideal gas law expressed as: PV=nRT where n and R are constants. T is absolute temp, NOT, REPEAT NOT, MEASURED FROM THE ARBITRARY FREEZING POINT OF WATER.
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Jack M.
Calgary, Alberta, Canada
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Yes I was joking. Nitrogen is 78 percent of air. I also was not expecting a scientific rebuttal of my 'temperature can even fool a tire gauge'. You 'ain't' going to get a proper pressure in your tires if you check them when hot, real cold, and especially if a tire or two is in direct sunlight. Whew!
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