Tire pressure and nitrogen refills

[Sportage EX]

Yes just regular air at the local BJ's Wholsale Club where I buy my gas.

[Dr Bob]

I worked at a lab where I could have filled my tyres with all sorts of gases had I wished. Nitrogen was cheap (maybe even free!), but I never bothered.

Unfortunately, the lab didn't run to Krypton, otherwise I might have been tempted. Inert gas, large atomic diameter, sexy name.

[engineered]

Just came across this Kia document in which they say that nitrogen filling tires is of little use.
https://www.kiatechinfo.com/files/33...0GEN%20058.pdf

Nitrogen Tire Fill:
This service appears to add little, if any, appreciable value to Kia customers. Tires should be filled
with dry compressed air using the specifications listed on the driver’s door jamb plate or in the
Kia owner’s manual. dry compressed air already contains approximately 80% nitrogen. Keeping
tires properly inflated with dry compressed air is sufficient to keep the tires in good condition
throughout their useful wear life.

[Server]

I keep my tires at 36Psi (cold). Never fill beyond 42.

Anyone heard what would happen if tires were filled with Helium?

Apparently, mythbusters filled a football with Helium and it went further when thrown compared with
just plain O2.

According to google, filling tires with Helium would save approximately 1.1Lbs per tire or 4.4Lbs total mass. The only drawback would be cold temps, (shriveled balloon effect ie. loss of pressure).

[engineered]

If they were filled with helium, they would leak even faster due to the smaller molecular size.
Also, the earth is running out of helium. We use a lot of it, and everything we use eventually floats into space.

As for tire pressure, Kia delivered our car at over 45psi, which is probably their shipping pressure. That means the dealer (427 Kia in Toronto) failed to properly complete the PDI, which included lowering the tire pressure.

[Wry 'Cuda]

Originally Posted by Server

According to google, filling tires with Helium would save approximately 1.1Lbs per tire or 4.4Lbs total mass.

Internal volume of a tyre is about 12 litres. Inflated to 40 PSI, that's about 35 litres of gas. At STP, air density is 1.2 kg/m3, so mass of air is 40 gram and mass of helium would be 6 gram. Total saving for four wheels of 136 g (5 ounces).

[Server]

Yes, thought it was a little high. Meant aprox 4.4 ounces