I fill mine with helium so that the car is lighter. The more helium I get into those tires, the lighter my car gets!
I use the N78 blend in all of my tires and cap them with the black valve stem covers. Recently, a friend of mine got a new car and I advised her to remove the lime green valve stem covers and replace them with the black ones as well. The green covers will protect the (Schrader) valves as well as the black ones but the latter will save you money in the long run since dealer mechanics are always looking for gullible people to sell throttle-body and transmission flush services to. That's why the valve stem covers are bright green. I guess if you're a Space Shuttle commander or an airliner pilot, you might want to put nitrogen in your tires but remember that Shuttle pilots are all unemployed now. The max take-off weight (MTOW) of the average airliner is in the hundreds of thousands of pounds, operating at three digit speeds (on the ground) while carrying something like 30,000 pounds of jet fuel in a very thin tube that is built to be as light as possible! Yeah. I'd use nitrogen too.....in passenger aircraft. Priuses operate mostly at two digit speeds, they weigh only about 3400# and their fuel load is only about 10 gallons. Simply put, there is no measurable, real world advantage in using the N95+ blends over N78. There are no true N100 blends. Since the tire is a rigid structure, you can't really get rid of all of the evil ambient air in the tire after it's mounted on the rim unless you purge them with multiple nitrogen "flushes" - which your dealer will be happy to provide you with.......free of charge! .......after they're finished with your throttle-body cleaning and transmission flush! YMMV!
According to the Internet, years ago they used to put Argon in tires of luxury vehicles. It leaks a little faster than N2, but they say the tires were more quiet on the road with the heavier gas in there. I suspect that today's radial tires are not the same.
If you want to make sure to have black valve caps on hand at Costco, where they give you green caps: take the current caps off just before handing the car over to them. The down side though, you eventually end up using the same caps for decades, pick up some new ones once in a while. I wonder also: maybe Costco also has black caps, maybe the valves come with them? Wouldn't hurt to ask.
I'd imagine any tire shop would have a surplus of caps that they wouldn't mind giving out. I've asked before and was given a handful.
If all else fails, you can always come off a buck and get 4 new caps at Walmart, where I believe you can get a 4-pack for something like 96 cents. I don't use Costco myself, but if I did I would simply remove and pocket the black caps before letting them rotate and balance the tires - or whatever service is required. Putting nitrogen in the tires certainly doesn't hurt anything at all, and you can put your caps back on when you're inspecting their work after they've finished. If all of this sounds like too much work - then simply stick with the green caps and let people snicker at you behind your back - but remember.....tires are pretty important. It hasn't happened to me personally, but I've had friends inspect tire work after the fact only to find loose lugs, non-rotated or improperly inflated tires, etc..... So....yeah. I'll take 30 seconds and put my caps back on. YMMV!
Yeah, except, that's more or less what I just said. To add to the list of gotchas that can happen at Costco (or any other tire shop): I watch a guy going around a car, putting the final torque on the lug nuts. He just went around them in order, no star-pattern for him. No big deal I guess, but not the way it's supposed to be done.
But Helium leaks much faster than even oxygen, in fact it is the fastest leaking stuff you could possibly use.
Larger because those hydrogen atoms like to hang out with a buddy (H2), whereas helium atoms are unsociable?
Just switched to dihydrogen monoxide, and I have to say, no more helium leaks! The car is a bit slower off the line though, and it doesn't like potholes.
That guy in the video is a bag of hot air and technically wrong about some of the things he said. He said the said the O2 molecule is only 2.5% smaller than N2, which may be semi-true, but the size difference is nonetheless enormous impact permeation rates (O2 has 3 to 4x faster permeation rate than N2). Since he was trying to downplay the permeation rate difference, he chose to obscure that fact. He quoted Consumer Reports leaks rates, but he divided the CR leak rates by 52 to quote a tiny 0.04 psia/week leak rate N2 vs. 0.06/week air which is actually 30% slower leak rate for N2. He tried to say these numbers are so small no one would notice, but he was manipulating the facts. I agree with him it's probably not worth paying $7.50 a tire, and a lot of the other hype benefits are not true. I agree with him some people over-sell N2, but he was full out under-selling it.
If O2 leaks out faster, than tires will increase their N concentration over time due to the reverse osmosis that is happening. My tires leak so slowly that I have to add air only once a year when it starts getting colder out.
...yes the tires do concentrate N2 over time, it's a slow process but helps to explain why there is not a bigger incentive for filling tires with N2.
