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I wonder what is going on with my air pressure in my tires. In the past I have only had to check the pressure occasionally, like once every few weeks and usually did not have to add air to either tire. Starting in the late Fall I found that even after just a few days, if I rode off without checking the tire pressure the warning light would come on, and sure enough, the tires were both down 5 or 6 psi from where I had left them (I usually keep both at 40). The other day, after not riding for several weeks, the weather turned warm and I didn't want to miss out on the chance of a ride so I unhooked the Battery Tender, pulled the rags out of the pipes, and fired it up. Then I remembered the tire pressure and laid down on the ground to check both, and sure enough, they were down to 30 in front and 28 in the rear. The tires are fairly new and have not had this problem until recently. It seems unlikely that I have damaged both rims that now allow some air to leak out, so I am wondering what might be the cause of the problem. Its especially annoying when I compare this to the Triumph Thunderbird I used to ride that I could go an entire riding season without having to add any air pressure at all.
 

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Loss of pressure over time is usually from debris in the bead seat area causing an imperfect seal or leaks around the valve stem at either the stem base seal or the valve seat itself.


If you haven't gotten new tires where the bead seats wouldn't have changed from when they seemed to hold pressure longer, I'd look at the valve stem.


Of course....losing 3-4 pounds a week could also be from a slow leak in the tire. I had a small nail in a tire once that sealed really well for a puncture but was still leaking slowly. It would only lose about 3-4 pounds a week.


Finally, the temperature and the amount of humidity in the air in the tire can cause a PSI difference. So....if you put air in on a 80 degree day with 70% humidity and then check again a day later when it's 40 degrees, the tire will probably show lower air pressure than the day before even if no air has escaped.
 

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Thanks for the good info. My bike likely will not be moving until Spring, but at that time I will be bringing it to my mechanic for some other matters, and I'll have him check and replace if needed the tire stems.
 

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motorcycle cowboy
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Check the valve cores, I had one loose. Also, with cold weather, air pressure goes down.
 

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I've never had a tire on any of my Wings that did not lose about 1-3 pounds of air per week. You might consider nitrous. Also, don't forget to check for leaks around the valve stem and it's base.
 

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Inflate tires to 40-50 psi. Remove the valve stem caps and soap test (a squirt of dishwashing detergent in a couple cups of warm water and apply with a paint brush) around the stems as well as all around the beads and tread. This should rule in or out a leak.
 

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Leak

I've never had a tire on any of my Wings that did not lose about 1-3 pounds of air per week. You might consider nitrous. Also, don't forget to check for leaks around the valve stem and it's base.
For me, 3 psi per week would be very high. I lose maybe 1 psi per week.

There have been repeated studies that say the air loss from a tire is essentially equivalent between pure nitrogen and normal air (which is 78% nitrogen) IF the air is dry.

A blurb from Edmunds says:
In 2006, Consumer Reports conducted a year-long study to determine how much air loss was experienced in tires filled with nitrogen versus those filled with air. The results showed that nitrogen did reduce pressure loss over time, but it was only a 1.3 psi difference from air-filled tires. Among 31 pairs of tires, the average loss of air-filled tires was 3.5 psi from the initial 30 psi setting. Nitrogen-filled tires lost an average of 2.2 psi from the initial setting. Nitrogen won the test, but not by a significant margin.

From this study, it seems like our tires are losing pressure faster than they should!
 

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For me, 3 psi per week would be very high. I lose maybe 1 psi per week.

There have been repeated studies that say the air loss from a tire is essentially equivalent between pure nitrogen and normal air (which is 78% nitrogen) IF the air is dry.

A blurb from Edmunds says:
In 2006, Consumer Reports conducted a year-long study to determine how much air loss was experienced in tires filled with nitrogen versus those filled with air. The results showed that nitrogen did reduce pressure loss over time, but it was only a 1.3 psi difference from air-filled tires. Among 31 pairs of tires, the average loss of air-filled tires was 3.5 psi from the initial 30 psi setting. Nitrogen-filled tires lost an average of 2.2 psi from the initial setting. Nitrogen won the test, but not by a significant margin.

From this study, it seems like our tires are losing pressure faster than they should!
Was the study done on m/c tires or car tires ??? Here in Florida, our weather from one day to the next can swing by 40-50 degrees in the winter. Our climate can have a lot to do with a drop in a tires air pressure.
 

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studey

Was the study done on m/c tires or car tires ??? Here in Florida, our weather from one day to the next can swing by 40-50 degrees in the winter. Our climate can have a lot to do with a drop in a tires air pressure.
This was done with car tires, not M/C tires, but since they are made of similar materials, I assumed their pressure loss should be similar.
 

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Temperature plays all sorts of games with machinery. I had an engine (brand new with less than a 100 miles on it) that would not leak for the dealer. Until I demonstrated that it will leak coolant when chilled to 0 degrees Fahrenheit, filled with coolant and pressurized. I was then granted a new replacement engine under warranty.

I would cool the tires down, put them at your riding pressure (40 was it?) and soap/water the heck out of them. It’s there, you just need to think like a air trying to get out and find it. Good luck.
 
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