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2012 Sportage EX
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Discussion Starter #1
What does everyone keep their tires filled at and what would be a good recommendation for higher MPG. My '00 Taurus was recommended at 33psi but I routinely filled it to 40-42psi. They weren't low profile tires so wondering if it is possible to do the same here? I won't mind a rougher ride to save a few MPGs.

I'm not liking the idea the nitrogen fills cost $40 a pop at the dealer so does anyone just add air to the already nitrogen in the tire and will there be an issue that will make the tire out of balance considering there might be different proportions of air versus nitrogen between all 4 tires if I decide to start just adding air to them?
 

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Cerato S Hatch Auto
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I stick to 36 PSI (cold); that gives a bit of "headroom" for pressure increase on the road. Many tyres have a recommended max. of 40 PSI.

As has been pointed out extensively on the forum, air is 78% nitrogen so mixing will be no worry. The alleged benefits of Nitrofill are small, so at $40, I wouldn't bother.
 

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2012 Kia Sportage LX, 6spd manual
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nitrogen isn't worth paying for. you're best off just checking your tires at least once a month
 

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2012 Kia Sportage
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My local Goodyear dealer charges $25 for nitro fill all four tires. Then free refills anytime you need it. Costco is the same on free refills when needed. So $40 each time you need a refill makes no sense at all.
 

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Nitrogen is technically better. Pragmatically, that still shouldn't matter.

Mixing the two isn't a problem, but reduces the oxidation technical benefit. Topping up nitrogen with air isn't adding much oxygen anyway.

If you have money to burn and don't mind being scammed, sure 40$ (or even 4x40$). If you want what's technically better (I usually do), find a reasonable price elsewhere. Otherwise, cash is better used elsewhere in life, or on directly-useful automotive products (rust inhibitor, new wipers, better oil or more frequent changes, etc.)
 

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2012 Kia Sportage Platinum Diesel
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don't burn your cash on Nitrogen. I keep them at 32 and the ride is noticeably smoother for it
 

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2012 Sportage EX
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Discussion Starter #9
I filled it up to 40psi and I like the lively nature of the ride now. 32psi would feel like I am stuck in molasses or running on 4 flat tires.
 

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Cerato
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I filled it up to 40psi and I like the lively nature of the ride now. 32psi would feel like I am stuck in molasses or running on 4 flat tires.
Well, that's good. I presume it was just air?

I've seen suggestions that apparatus that's supposed to fill your tyres with nitrogen is just a sham collection of tubing that supplies plain air; that's a scam x 2.
 

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Cerato
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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.
 

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2012 Kia Sportage LX, 6spd manual
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Just came across this Kia document in which they say that nitrogen filling tires is of little use.
https://www.kiatechinfo.com/files/331/2063/TSB GEN 058.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.
 

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2K13 Forte SX Lux yada yada yada...
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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).
 

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2012 Kia Sportage LX, 6spd manual
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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.
 

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Cerato S Hatch Auto
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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).
 
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