Can someone explain what green caps on the tyre valves mean - evidentally there is some gas in the tyres.Can you still fill/top them up as per normal at the petrol station.What is the purpose for doing this, we just bought this car & it has the grren caps on it.Thanks for any advice.
matarautrader,
Dec 10, 10:08am
My wifes car came with pink valve caps.
franc123,
Dec 10, 10:14am
They've been filled with pure nitrogen, its basically a money making extra the tyre shops have got into in recent times, its not necessary. Yes you can pump the tyres up with normal air, which interestingly enough contains a lot of nitrogen anyway.
vibr8a,
Dec 10, 10:15am
its full of nitrous oxide, meant to be better than regular compressed air and give you better efficiency etc. can fill them again at most tyre shops, I think Tonys do it, although I would trust them with nothing. not sure if you can just fill with air as well. dont see why not.
morrisman1,
Dec 10, 10:16am
but F1 uses nitrogen so it must be beneficial for my nissan sentra! With nitrogen I'll be able to pull 4G in the corners! Out-handle any crappy peugeot too cos I heard they only do 3.5G
johnf_456,
Dec 10, 10:28am
and to add the air around us is 78.082% (according to wiki)
franc123,
Dec 10, 10:32am
Thanks for that, yes I knew it was a high percentage.
esprit,
Dec 10, 10:44am
Dry nitrogen is generally more stable with temperature than compressed air, giving less pressure variation as the tyre heats and cools. Essential in high-level race cars, completely useless in anything resembling a road tyre.
hpaul,
Dec 10, 10:52am
Mostly this.
Although heat based pressure variations of 10psi+ can occur in road tyres filled with 'normal' air and that can make a difference, even in road driving.
harry353,
Dec 10, 11:16am
10psi! Only if they are incorrectly inflated.
esprit,
Dec 10, 12:48pm
I can fill my track car's tyres on a cold morning and then have the rubber practically melting off them on the track and I don't see 10PSI difference, 7 at most! If you fill your tyres on a moderate temperature day, I'd say that on a cold morning you might be 1-2 PSI down at the most, and on a very hot day or with some aggressive driving you might be 1-2PSI up. which is not enough to make a meaningful difference on most cars.
hpaul,
Dec 10, 6:40pm
Testament to Colin Chapmans 'add lightness' theory!
We recently measured pressures and temperatures on 20 cars at a trackday and the smallest pressure rise was 6psi, the biggest 17psi.
A heavily laden or 'spiritedly' driven road car can show a 10psi gain/loss.
Enough to notice the pressure stabilising benefits of nitrogen! Probably not.
Diligence in regularly checking pressures will serve 99% of motorists better but those green nitrogen dust caps make Porsche owners feel like Schumacher on their daily gridlocked commute.
elect70,
Dec 11, 3:07am
Um dont think sonox is form of supercharging for drag race enginesnot for tyres .
sas777,
Dec 11, 3:37am
Pretty sure some of the big dump truck operators use nitrogen for inflation over here in Oz. The theory is no oxygen to feed a fire if the tyre is burning.
daryl14,
Dec 11, 5:05am
WTF You need to delete that post on the grounds of stupidity, and someone who doesn't know any better might actually believe you.
Yeah they fill tyres up with compressed fuel and hope they don't get too warm or explode. You twit face.
sr2,
Dec 11, 5:15am
Nitrous Oxide is not a fuel; it is an oxidising agent. (Level 1 NCEA Chemistry).
daryl14,
Dec 11, 5:17am
Ok. what evs, doodey head. It could still explode in a tyre could it not!
jmma,
Dec 11, 5:23am
That made me laugh, what a gas (o:
the_chooky,
Dec 11, 6:23am
Way back in the 70's when I worked at Pt Hedland one of our Austin ex army trucks needed a tyre pumped.only thing I could find was the acetylene bottle. Was still going fine when I left.
sr2,
Dec 11, 6:35am
LOL, I love it. You should have mixed ina little oxygen, just get a neutral flame, snub it out and fill it up??
morrisman1,
Dec 11, 8:07am
nup. Its basically super enriched oxygen, meaning you can add a crap load of fuel and hence make lots of power. It does nothing without fuel
naphtha,
Dec 11, 9:08am
Green caps for right side of car, red caps for left side.Black for spare tyre.
pebbles61,
Dec 11, 9:38am
Said savings are then spent on getting nitrogen lol
daryl14,
Dec 12, 4:37am
Ok fine, so if super enriched oxygen came gushing out of a ruptured tyre, what do you think would happen! Hmmm heat and concentrated oxygen. Nope, sounds safe as.
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