lumpy790
York, SC
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I am anal about checking my TV's tire pressure before every trip. My TV is a Ford E450 with dual rear tires that call for 80 PSI and after I bought it I added the extentions so I could get to the inner valve. They worked great till ..... I took it in to the dealer and had them rotate my tires.....then the extentions started leaking. I chased the leaks till I took the tires off and adjusted the extensions my self. They are really touchy and a 1/4 turn can make all the difference.
One thing I have found interesting is how much the outside air temp affects the tires pressures! If its cool out 50's-60's the pressure will drop 5-10 psi! If I do the tire pressures when its cool out and it gets warmer say 80's the pressure is up 5-10 psi.
Any one else experience this?
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beermanjoe
Pa
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Driving it will heat the tires up and make the pressure rise also.
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lumpy790
York, SC
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true but they always say to check pressures when tires are cold.
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Cool Canuck
Winnipeg, MB, Canada
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beermanjoe wrote:Driving it will heat the tires up and make the pressure rise also. This is allowed for in the tire pressure charts and like previously posted, this is why you check pressures when cold.
The generally used number is 1 psi for every 10F. It seems to be more when I check them.
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K3WE
Missouri
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lumpy790 wrote:Any one else experience this?
I believe everyone else experiences this.
Chemists would say: "PV = nRT" where T = temperature and P = pressure...a fairly direct relationship.
I also belive that the elusive middle ground is to check the pressure on a good hot day in the spring (cold tires though) and consider yourself set for the summer.
Do the same on a good cold fall day and consider yourself set for winter.
The periodic check ups are good- but yeah, the pressure will vary from hotter to cooler days.
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Berky
Middletown, DE
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The 1 PSI per 10 F rule is for passenger tires inflated to 30 PSI or so. For RV tires inflated to 65-80 PSI, the rule is 2 PSI per 10 F. So an ambient temperature change of say 25 F is 5 PSI. Add to that the hot sun on a black tire, and you might have another 2-3 PSI on top of that.
I set my tire pressure shortly before hitting the road. I set them for 60 PSI (LRD tires). BUT, I SUBTRACT 2 PSI for every 10 F that the morning temperature is below the expected afternoon driving temperature. So for example if I'm pulling out when it's 70 F, but I'll be driving in the low 90's, I set the tire pressure for 56 PSI.
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Photog101
Garden City, Michigan
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I had problems with valve extensions on my truck and I changed the type of air gauge that I use. I went to a double foot with a straight on one end and the 30* on the reverse side. I got rid of the problematic extensions and life is good.
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motorcycle jack
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I have a TPMS system on my tires. And yes the temperature really affects the tire pressure. When driving down the road, my normal 120 psi tires will be in the mid 130's, a 15 psi increase from road heat. So your 5-10 would be expected in a temp change of 15-20 degrees. But you are to check the pressure when they are cold - never check or add when hot because you will not know what to expect.
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lumpy790
York, SC
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Photog101 wrote:I had problems with valve extensions on my truck and I changed the type of air gauge that I use. I went to a double foot with a straight on one end and the 30* on the reverse side. I got rid of the problematic extensions and life is good.
Tried one of thos but still could not get a good reading without the edge of the guage leaking ..... but this makes me wonder.
I recently replaced the rubber valve stems with metal ones.... yep they broke but caught them before any damage and fixed them my self on the side of the road. Not easy but Motorcycle tire irons can break down a tire bead for instalation.
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Clay L
Sioux Falls, South Dakota
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When I bought new tires a couple of years ago I had them install metal Dually Valves. Pricy but they make adding and checking air so much easier I wish I had done it years ago. They come with rubber stabilizers they fit in the wheel handholds.
See them HERE
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