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I’m watching these videos of folks removing tires and they typically take out the valve core and reinflate the tire with a decent air compressor. They don’t really get into the details but I’m curious what specifications one would need on their compressor unit to succeed in reseating a typical car or truck tire back onto the rim.

It seems like compressors have an SCFM rating (standard cubic feet measurement), which is their air flow rate, which should be applicable here. I also understand that when the bead is off the rim there will be leaks but with a fast enough air volume crashing into the tire the compressor flow rate will dominate and will achieve a net positive air flow which will inflate the tire till it reseats itself onto the rim.

I don’t own an air compressor currently but for the above job what sort of minimal unit would get the job done? I welcome any anecdotes and personal experiences for any specific models or rough memories on the subject.

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    "SCFM" is actually standard cubic feet per minute. It has to do with the molar flow rate of a gas versus just air CFM. Jan 2 at 23:11
  • A decent sized air tank is probably more important than a high CFM, from the compressor, since you don’t need a constant high flow rate, you just need a few seconds of lots of air.
    – HandyHowie
    Jan 2 at 23:14
  • Thanks for the tip, I thought that acronym expansion looked suspect, there was no rate units in it. I found it over here unfortunately aircompressorclub.com/what-is-scfm-on-an-air-compressor
    – jxramos
    Jan 2 at 23:14

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I agree with @HandyHowie from comments in that a decent sized air tank is more important than high CFM or SCFM when it comes to compressors. The more important thing is PSI. You have to have enough air pressure to overcome the beads so they can seat on the rim. Since most passenger tires only require around 32-35psi of air pressure, you just need a bit more than that to seat the beads. Soapy water is used to help in the process to both help with the sealing as well as lubricant so the bead will pop onto the rim more easily. This PDF from the USTIRES.ORG states you shouldn't inflate beyond 40 psi of pressure, however, I find that a little odd. Some tires require more air pressure than 40 psi for normal use, so going beyond it in those cases does not seem detrimental to the tires. All that is needed is for the bead to seal on the rim and air pressure does the rest. It really doesn't matter how fast the air moves into the tire at that point. You just need enough PSI to overcome the bead on the rim and you're golden. This probably includes most home use air compressors on the US market.

The only time I've seen a large quantity of really fast moving air used to seat a bead is on oversized (offroad) tires. The kind you see rock crawlers and such use. The reason for this is, because the tire themselves are very flexible which makes it hard to get both beads to seat at the same time just trying to man handle them. To seat the bead on these types of tires, you would use something like a tire bead seater. This forces a large amount of air into the tire cavity very fast, which expands the tires just enough to get the beads up to the rim, then the regular air compressor is used to get the beads onto the rims. A compressor alone is not going to be able to do what the bead seater can in this case.

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  • Would a 3Gal unit pull it off? I see these so called pancake compressors round that size. There’s also some smaller units at 1 and 2 Gal. Bigger stuff exists too like 6, 8, 10, and 20 gallon units. The little air inflators probably wouldn’t cut it right? Something like this unit harborfreight.com/…
    – jxramos
    Jan 3 at 4:33
  • @jxramos - Yes, a 3 gal pancake compressor can do this if it can get about 40 psi and you can get the beads to seal on the rim. Remember, it's the PSI which gets the beads to seat on the rim. Jan 3 at 13:49
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    View more videos. A small home air compressor is all that's needed. The trick to bead sealing is technique. Synthetic rope tied around the tread and a piece of wood to tighten rope will expand both tire beads against the inside rim. Use enough tire soap, WD-40 or whatever to allow rubber to slide for bead sealing, enough to have compressed air take over, sealing while inflating. Bounce the tire to help with rubber to rim contact. Leave the valve stem in. The first time is the hardest until you figure out each step for easy bead sealing.
    – F Dryer
    Jan 3 at 16:53

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