36 degrees and differential tire pressures???

[bncinwv]

To say I was confused is an understatement. I went to the rig in mini-storage yesterday evening to put the battery back in, secure the dishwasher for travel and to check the tire pressures. Outside temperature was a balmy 36 degrees. Tire pressure on the off side was where I expected, 97-98 psi (don't panic, they are 614s inflated according to the loading inflation chart). The entry side of the rig however, had pressures of 88-90 psi. Both tires on the off side registered exactly the same which made sense since I inflated to 100 psi when it was about 60 degrees last fall, the entry side however confused me even though they also registered exactly the same - I interpret the same readings to show that there has been no leakage. I had the ever trusty Harbor Freight air compressor and remedied the situation by inflating them to 98 psi to match the other side. The only thing I can figure is the entry side was more shady during the course of the day and in turn the off side was exposed to whatever sun there was and perhaps that resulted in the tires holding the pressure a little better. I will re-check the pressures Saturday morning before pulling the rig to the dealer, so hopefully that will add a little more info (or confusion) as to what may have occurred.
Bingo

[7.3Ford]

Bingo,

I have found the same thing, sunny side is always 5-8 lbs higher. I now try to put air in tires 3 hours after sun down.

[bncinwv]

Kinda what I was thinking, I am thinking I will be letting air out of the entry side Saturday morning in order to get both sides equalized. Another interesting thing I encountered had to do with the air compressor. It would not start if it was hooked to the tire, possibly due to the high pressures. I could start the compressor and then attach the air nozzle to the tires and it worked fine. Chinese engineering at it's best??
Bingo

[DarMar]

I try to adjust the initial season tire pressure on a cloudy day to get a more even reading. Since we are new to the 614's I haven't adjusted the air with the portable compressor yet but will attempt that next week. As you have experienced, I fully expected that type of difficulty with the small portable, perhaps ours won't even pressure to 95 psi, we will see.

[firetrucker]

Big air compressors have a check valve and dump valve that releases the pressure in the line. That's so the compressor can start easily when working against high pressure. With your portable compressor, disconnecting the hose is the manual dump valve.

Bob

[Trailer Trash 2]

the air is warmer on the one side of the RV and it expanded more psi. the other side is colder and creates less pressure. that the way I would look at it, try an experament with a piece of 3/4" plywood covering the tires on the warmer side at night then check them when the sun is up on that side and see if they are the same psi

[bncinwv]

That would be a good experiment, Don. I would do it out of curiosity if the rig was not a twenty minute drive from the house each way. Your statement does make sense since I am thinking that temperatures are usually 10-15 degrees cooler in the shade and who knows how hot the black tires get when in the sunshine. I will post the pressure comparison when I double-check them Saturday morning before pulling the rig off the mini-storage lot. Still have a hunch I will be letting the 10 pounds back out that I put in, but we'll see.
Bingo

[camper4]

Seems to me what you are seeing is normal. I have temps change my tire pres when I travel to the Fl Keys from upstate NY in late Dec. I start with 80psi and every morning before I start the next leg of the trip, I check pressures. As things warm up going south, I have to let air out to keep my cold starting pressures to 80psi.
On the return trip in April, I have to add air each morning. Some days it is as much as 8 pounds off. TV is same way.

[ols1932]

Bingo,
I wouldn't be hasty about decreasing the pressure in the sunny side tires. I'd recommend you take a look at the pressures when both sides of the rig are in somewhere the same situation. In other words, sun beating from front to back or back to front. I check mine this way and I never notice any more than one or two pounds difference.

Orv

[bncinwv]

Orv, it is the entry-side (shady) tires that I added the 10 pounds of pressure to, that is the side that I have the hunch will be unequal in the morning after the rig sits in 30 degree temperatures overnight. I think if I would have left them as they were then I would have the same pressure on both sides in the morning. I will post what I find, but I have a strong hunch that I should not have added air at all.
Bingo

[grampachet]

I have wondered about the recommendation that you check the pressure cold.
So what is cold, there is a big difference between 30 and say 70.
When I check and top up at 30 degrees and in driving the tire reaches 70 degrees
The pressure has increased more than 19 to 20 pounds according to the TST readout.

[CamillaMichael]

The year before last, when we were camping in Maine (the am temps were usually under 40 degrees) our SUV was parked so that the morning sun hit the passenger side...we had a built in tire monitoring system so it was easy to check the tire pressure and noticed that every morning the pressure was from 8 to 10 psi higher on the passenger side.

[HamRad]

The environment that the tire is in makes a big difference in pressures/temps. My Pressure Pro system clearly shows the difference between the sunny side vs the shady side even as we travel down the road. Travel safely, Dennis