So what is the best temps to check pressures. If I check when 50* and check another day when it is only 30* there is about 4lbs difference. Actually that is the difference shown on my TST tire pressure monitor. How close do you really need to be to the magic number.
Ken
From my old days as an aircraft mechanic, tire pressure does increase under load (not talking about the temp/pressure increase due to operation). Goodyear specifies the pressure for a tire/wheel assembly not mounted on an aircraft or with the aircraft on jacks. They say to add 4% to that figure when the aircraft is resting on the tires. For vehicle tires it may be a different percentage.
For an explanation of tire pressure behavior, look here.
Dave & Gean
2007 Tundra DC 4X4 5.7
2009 Cougar 245RKS
370 watts ET solar
Rogue 3024 MPPT controller
440 Ah battery bank
ProWatt 2000 inverter
What's odd is, I air my tires up to 80 PSI, then load 4000lbs of camper in the bed and the tires still read 80PSI.
Follow me as I full-time the Redneck Way at The Journey of the Redneck Express CBChannel 17Redneck Express '1992Dodge W-250 "Dually" Power Wagon - Club Cab Long Bed 4x4 V8 5.9L gashog w/4.10 Geared axles '1974KIT Kamper 1106 - 11' Slide-in
Tires are rated higher with higher psi; Air them up before you add the weight. Air bags: I back under the TC, inflate the bags, lower the TC and adjust as needed. Air Bag PSI depends on your truck and camper.
12thgenusa wrote: From my old days as an aircraft mechanic, tire pressure does increase under load (not talking about the temp/pressure increase due to operation). Goodyear specifies the pressure for a tire/wheel assembly not mounted on an aircraft or with the aircraft on jacks. They say to add 4% to that figure when the aircraft is resting on the tires. For vehicle tires it may be a different percentage.
For an explanation of tire pressure behavior, look here.
I agree. Think of it like a pneumatic cylinder, if it's starts with a specific volume of air(0-psi), as it is compressed, the pressure increases. Now, the amount of air injected into a tire doesn't change but the volume of a circle reduces(cubic feet or inches).
Reality, not enough in a tire that we would have to worry about, thus the readings others have noticed when checking loaded/unloaded.
But factually, you are correct.
I air my tires and bags up on the way to pick up the camper. About 45psi in the bags (I store the camper almost at loading height on stands). When I load the camper the tire pressure doesn't change enough to notice, but the little air bags do. After loading the camper, I let out enough air from the bags that the overload springs touch, or they are just shy of contacting.
2006 F150 SuperCrew FX4 - Bilsteins, Hellwig sway bar, Firestone air bags, BFG KM2s, 4.56 gears, F&R lockers, Torklifts w/ Fastguns
2011 Travel Lite 700
It is not always needed to air up to 80 psi for E-load tires.
Especially Americans often take heavyer tires on their Camper, for instance if original is D load they take E or even F load tires, thinking this is better.
But on softer ground the D load gives more gripp and langer surface on the ground, and more comfort.
But the tires together must bare the GAWR ( Gross axle weight ratings) + a reserve of minimum 10% , so somethimes 1 -load more can be usefull. Also mind that an E-load tire with the same sises needs a higher pressure for the same load then a D-load tire.
The needed tire-pressure can be calculated with the save European Formula that I got hold of once, and made spreadsheets with. public map of skydrive 2nd from bottom
Open the spreadsheet 2nd from bottom on my skydrive. For this click on the I in a circle at the end of the line , then in the right barr at download, and open it after download with Excell or compatible programm. And from this link you can navigate my complete public map of skydrive/hotmail for more ( A lot about tire-pressure).
Offline
