BS: 'kpa' to 'psi' conversion help needed

Subject: BS: 'kpa' to 'psi' conversion help needed
From: Blackcatter
Date: 24 Sep 03 - 11:55 AM

Hello,

I have a Chinese motor scooter and want to keep the tires at the correct pressure. Unfortunately, the manual tells me they need to be at:

147kpa and 171.5kpa

I've tried to find a conversion to pounds per square inch (PSI) but to no avail. No one seems to recognize "kpa" and when I put the numbers in standard kilos per centimeter, per meter, per milimeter I get numbers that are totally off the mark. Any help?

Thanks in advance.

Subject: RE: BS: 'kpa' to 'psi' conversion help needed
From: Amos
Date: 24 Sep 03 - 12:00 PM

KPA are kilopascals of pressure. Do a web search for on-line conversion sites -- there are several.

A

Subject: RE: BS: 'kpa' to 'psi' conversion help needed
From: Amos
Date: 24 Sep 03 - 12:04 PM

Here's a conversion URL: http://www.metrication.com/.

A kiliopascal is equal to .1451 pounds per square inch.

A

Subject: RE: BS: 'kpa' to 'psi' conversion help needed
From: Blackcatter
Date: 24 Sep 03 - 12:07 PM

Thanks - that did the trick.

Though the pressure seemed a little low . . . 21 and 25 PSI.

Subject: RE: BS: 'kpa' to 'psi' conversion help needed
From: JohnInKansas
Date: 24 Sep 03 - 01:44 PM

The conversion is pretty simple, and seems to have been implemented. As a side note, all US auto and truck tires are marked on the sidewall with the "rated" inflation pressure in both kpa and psi, so you can check a neighbors auto (if all you have is your Chinese vehicle) to get a "good enough" conversion by simple division.

It's become quite common for pressure gauges to have both scales, as well. Even my 20 year old Coleman camp pump (12 volt dc "Inflate-All") has both scales on the gauge.

Rather low inflation pressures are quite common on light weight (and lower speed) vehicles, especially stuff with fairly "fat" tires. Garden tractors, mowers, and wheel barrows often spec 8 to 10 psi, which can be quite difficult to maintain. Many low pressure tires include a tube, since the pressure is not sufficient to "seal" the rim with a tubeless tire installation. A problem to watch for is that the lower pressures often don't seat the tire/rim joint well enough to keep moisture out of the tire; and rim corrosion, when moisture gets in, chews up the tubes. (Old bicycles - 40 to 90 psi - sometimes have the same problem. It's really the tube - not just the pressure - that's the cause of it.)

Several US auto manufacturers in the '50s and early '60s were specifying 22 to 26 psi inflation - to get a "softer" ride, but the tires wore out pretty quickly at those pressures. The same tire, inflated to the "sidewall pressure" of 28 to 32 psi would run about twice as far for the same tread wear on many vehicles, and the higher inflation pressures were very commonly used (who actually reads the manual?).

John