Topping off 22.5 tires.

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garyb1st

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Sears 150 psi hotdog compressor will not air tires beyond 78 lbs.  Was told the only way to fill tires this large was to lift the tire off the ground.  Haven't tried doing that.  I know I can get the front tires off the ground but doubt I can do more than take some of the weight off the rear dually's.  Am I doing something wrong?  The last time I tried to top off the tire, it stopped at 78 lbs and after two minutes of continued airing, it was still 78 lbs. 

On an old thread, I read at best, all I needed to do was fill the tire enough to get to a service station.  If that is true, I'll leave the heavy compressor and go with a smaller portable compressor. 
 
If you've got a 150 PSI compressor, it should continue to fill the tire until it get's to 150 PSI. If it doesn't you either have a problem with the compressor or you have a pressure regulator problem.
 
No problem at all here with my 150 psi compressor airing up my tires to about 110 psi or more.


Bill
 
I have a Craftsman portable 125psi compressor and fill my 22.5 tires to 110lb with no problem.  I use an air chuck that clips on to the valve stem, set the pressure regulator to 110lbs.  The compressor shuts off when the pressure is reached.
 
Helmerb said:
I have a Craftsman portable 125psi compressor and fill my 22.5 tires to 110lb with no problem.  I use an air chuck that clips on to the valve stem, set the pressure regulator to 110lbs.  The compressor shuts off when the pressure is reached.
Click to expand...

I use a 130psi compressor to air up my front tires to 110psi.  The trick I've discovered is to connect the air chuck while the compressor is running and to hold the trigger on the chuck open until the desired pressure is achieved.  If I don't keep the trigger open continuously the compressor will shut off when it reaches 130psi even though the tire isn't yet at that pressure. I have a professional quality air hose but the flow through the hose and into the tire is slower than the rate the compressor can pressurize itself.
 
Lifting the tire off the ground won't change things one iota. The psi is the same either way, as is the amount of air needed to fill it.  Whomever told you that should be ignored if you need tire tech advice in the future.

You didn't say what psi you need to achieve on those 22.5's - could be anywhere from about 75 to 120. A 150 psi compressor should be able to do anything in that range, though some of them will be horribly slow much above 90 psi.  It's cheap and easy to design a compressor with a high psi rating, but expensive to do one that does both high psi and high air volume (high cfm rating).  There are little hand operated bicycle pumps that can do 200 psi, but blowing up even a car size tire would take forever.
Filling a large tire requires a lot of air volume, the CFM (cubic ft/minute) rating on a compressor. As pressure goes out, cfm goes down, so a compressor that can do 100 psi @ 2 cfm is one of the better models (and more expensive than a lower cfm model).
 
Will your compressor actually compress air to 150# in the tank? If so, that means the compressor is doing it's job correctly. If you can't get the 150 psi to come out of the tank, then there's most likely a problem with the regulator on the output side.
 
Gary RV_Wizard said:
 
Lifting the tire off the ground won't change things one iota. The psi is the same either way, as is the amount of air needed to fill it.
Click to expand...
  Just aired the tires to about 85psi.  Blew out the air filter which didn't look dirty.  Other than that, didn't do anything different. 

Whomever told you that should be ignored if you need tire tech advice in the future.
Click to expand...
  Duly noted.
 
Gary RV_Wizard said:
Filling a large tire requires a lot of air volume, the CFM (cubic ft/minute) rating on a compressor. As pressure goes out, cfm goes down, so a compressor that can do 100 psi @ 2 cfm is one of the better models (and more expensive than a lower cfm model).
Click to expand...

Just checked the specs on my Hitachi compressor.  It's rated at 4cfm at 100psi.  I used to use it on the farm and it was small enough to put in the basement of the MH.
 
Gary,  if you can't get the pressure up, then goat's comment:
If you can't get the 150 psi to come out of the tank, then there's most likely a problem with the regulator on the output side.
Click to expand...
reminds me that you probably have two gauges on your compressor, and there is probably a knob or such you can twist to adjust the output pressure. Does yours have those items? Perhaps, as indicated above, you need to adjust the regulator.
 
Gary, is this the one you have?  If not, can you go to the web site for Sears and find the one you have.

https://www.sears.com/craftsman-6-gallon-oil-less-pancake-compressor-and/p-00916575000P?plpSellerId=Sears&prdNo=2&blockNo=2&blockType=G2
 
Apparently it's working.  Takes a while but I was able to put an additional 5 lbs in both front tires in a couple minutes.  But if I had to air them up to 100 lbs, I'd have to have my wife bring lunch. 
 
You might want to upgrading to a compressor like this one.
https://www.amazon.com/Viair-40047-Automatic-Portable-Compressor/dp/B004B68XGC%3FSubscriptionId=AKIAIOZEUVJBKODOGDMA&tag=rvgyoucha-20&linkCode=sp1&camp=2025&creative=165953&creativeASIN=B004B68XGC/ref=as_li_ss_tl?ie=UTF8&linkCode=sl1&tag=rvgyoucha-20&linkId=36b71a910026af05aff4e9da695a352e
Bill
 
Apparently it's working.  Takes a while but I was able to put an additional 5 lbs in both front tires in a couple minutes.  But if I had to air them up to 100 lbs, I'd have to have my wife bring lunch. 
Click to expand...
Then it's simply an inexpensive,  low flow (CFM) compressor as I described earlier.  Probably less than 1 CFM at 80+ psi.  I would suggest one rated for at least 2 cfm @ 90-100 psi when & if the budget permits.  Here's a decent one that sells for $100 or less at many places - I think I paid $99 at Lowes a few years back.
https://www.homedepot.com/p/Porter-Cable-6-Gal-150-PSI-Portable-Electric-Pancake-Air-Compressor-C2002/203162815
 
This is the one I have.  https://www.sears.com/craftsman-3-gallon-portable-air-compressor/p-00915362000P?plpSellerId=Sears&prdNo=3&blockNo=3&blockType=G3#

Hard to read but it looks like 2.4 cfm at 110 psi.  I also have a heavy duty 25 foot air hose.  Not sure about the quality of the air chuck.  Think it was a kit from Harbor Freight. 
 
I don't see a CFM rating in the owner manual or sales page, but maybe I missed it?  In any case, it states a cut-in pressure of 105 psi, so 105 is the max psi it can sustain. It can produce 135 psi part time, but that gets very frustrating cause  the pressure falls to 105 as you pump air and the flow rate falls with it.
 
garyb1st said:
This is the one I have.  https://www.sears.com/craftsman-3-gallon-portable-air-compressor/p-00915362000P?plpSellerId=Sears&prdNo=3&blockNo=3&blockType=G3#

Hard to read but it looks like 2.4 cfm at 110 psi.  I also have a heavy duty 25 foot air hose.  Not sure about the quality of the air chuck.  Think it was a kit from Harbor Freight. 
Click to expand...

I had an old painter tell me once that every length of hose you put on a compressor will lower the rated output of the compressor by 10 PSI. Not sure if it's true or not, but when I used to use a stand up Sears compressor to to remove tires on the Jeep for rotation, I always worked better when I used a 10' hose instead of a 25 or 50' hose.

That may be affecting the rate of fill of your small compressor.
 
A compressor - any tank compressor - will fill the tank to a preset psi, then shut off.  It will start back up when the pressure falls below the second pressure setting.  Compressors are labeled by this higher number, when, in fact, they can only maintain this lower pressure.

If you need to fill tires to 90 psi, a 100 psi compressor is likely too small, as the cut in limit will be less than 90 psi.  A 125 psi compressor is a better choice.

Note regardless of the size chosen, the regulator must be set to deliver that pressure!

DocJ had a great idea!  New idea to me.  If the air is going to the tire when the compressor kicks on, the tire becomes part of the tank, as they are connected, and you CAN get higher pressures into your tire, assuming air can go through the hose as fast as it is compressed.
 
A compressor that is 1 psi more than the desired tire pressure will eventually fill it. The key is "eventually", and you need a lot of patience & perseverence!    Before that happens, the air chuck will probably slip off the valve and lose some pressure, or the compressor pump/motor will overheat or the power wires will melt... you get the picture!

 
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