Inflating a tire with an air compressor

[Augusto Orosco]

I have a porter cable 150psi /6gal compressor. It came with one of those attachments to inflate car tires. Does anybody know at how many PSI should I set my compressor in order to inflate my car's tire? I set it to 90-100 psi for driving nails; but I don't know if this would be excessive to inflate a tire up to 30PSI.

Thanks!

[Mike Marcade]

You don't really need any more pressure than your tire requires. Just set your regulator at a little more than your tire needs than inflate it. Just check it with a reliable tire gauge.

[Leonard Clark]

That should be fine. Just put a little bit in at a time. Check the tire with the proper tire gauge. Over filling can happen.

[Robert Payne]

Harbor Freight (or similar places like Northern Tool) have tire inflators with a built-in pressure gauge for less than $10. I use one with my P-C pancake and it reads off the tire pressure as you inflate.

[Jim Becker]

I use a device like Robert references for filling tires so I know exactly what the pressure is in the thing. (Within the accuracy of the particular gage)

[Randal Stevenson]

Most garages have their setups for the tool pressure. They just swap the tool, with a tire chuck and use it at that pressure (it fills quicker).
While I prefer a better gauge, I know several people who have been happy with the tire gauge that when you let off the trigger, it shows the current tire pressure, and HF sells those. The biggest thing, is use ONE gauge, as two normally don't read exactly alike.

[Jason Roehl]

DON'T set your compressor's regulator to the pressure you desire in the tire. It will take much longer than necessary to fill because the regulators on small compressors are usually pretty cheap and pretty iffy on pressure anyway. If your tire is at 30 PSI, and you set the regulator to 35 PSI, it can take a long, long time to equalize. Instead, use a good dial gauge and just fill for a while with your compressor set somewhere around 100 PSI, then check. Repeat as necessary. After you do this a while, you start to get an idea for how fast the pressure in the tire is rising. And, should you happen to overshoot by a few PSI, it's not a big deal (their pressure will go up once the tires get warm from driving anyway), just let it out--most gauges I've seen have a little nipple on them for just that purpose.

[Augusto Orosco]

Thanks everyone for their input!

DON'T set your compressor's regulator to the pressure you desire in the tire. It will take much longer than necessary to fill because the regulators on small compressors are usually pretty cheap and pretty iffy on pressure anyway. If your tire is at 30 PSI, and you set the regulator to 35 PSI, it can take a long, long time to equalize. Instead, use a good dial gauge and just fill for a while with your compressor set somewhere around 100 PSI, then check.

Jason: That's exactly what I was wondering! I have a good digital gauge which I will use to make sure I don't overinflate.

[John Mihich]

Jason has the right approach. I use to work in a garage and never worried about incoming presure, just used a guage to get the right amount of air. You can always let some out if you put too much in.

Now for bikes it's real easy to over inflate. I tend to be a little careful there. It's real loud when they pop.