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Originally Posted by hayaku
after reading that, how can you still say its snake oil? sure, they agreed it won't make much of a difference on grandma's roadmaster... but the benefits are real...
i have first hand experience on my race car. on a 110 degree (air temp) day in socal on desert racetrack, i ran nitrogen versus my buddies that had typical compressed air... after a 20 min session, my tires went up 2 lbs in pressure. EVERYONE else ran up 15-20 lbs of pressure...  so everyone else spent all of their rest sessions tweaking and tuning their tire pressures and suspension while i just rested...
and my car was fastest on the track with that group so the argument of me driving more conservative versus the rest of the attendees is not gonna work...
for those that don't drive hard or can't even feel the difference of uneven tire pressures (read 99% of drivers out there), nitrogen isn't going to do anything for their performance... but it is going to save the tires for those in very humid areas and store their cars alot... |
By my calculation the tire temperature would have to increase from 110 F to 342 F to increase the tire pressure 20 lbs from a starting pressure of 35 lbs. I'm not a racer so I don't know if that's possible or not. Your tire temperature would have to be 132F to get a 2 lb increase in pressure, which seems reasonable.
My calculations do not account for the presence liquid water in the tire. It's more complicated in that case. Water vapor (humidity) make no difference as it behaves exactly as O2 or N2 behaves with regards to T vs P.
My take on the N2 fill is if it's free then why not - it can't hurt. If you have to pay and you are not racing then it's a waste of money. This is assuming you don't normally fill up your tires with a crappy air compressor that spits out slugs of liquid water once in a while because it doesn't have an air dryer.