RajDatta

Found all cars to be down 4-5psi. Just a friendly reminder .
Raj

Fox944

My tires are nitro filled, so they arnt nearly as affected by temperature changes. I would reccomend everyone nitro fill their tires.

*Air pressure is much more consistent & the tires require much less maintenance.

brad@tirerack.com

Good tip. Mine were down 4 lbs. this AM....

Damian in NJ

Not a big difference on street tires, but race cars are another story. 1.3 psi difference over twelve months between compressed air and nitrogen street tires.

Consumer Reports wanted to find out if nitrogen is worth the price, so we purchased a Nitrogen Inflation System and checked out how well the inflation held up over a one year period. We evaluated pairs of 31 tire models of H- and V-speed rated, all-season tires used in our tread wear test from 2006. We filled one tire per model with air and the other with nitrogen. The test was quite simple: fill and set the inflation pressure at room temperature to 30 psi (pounds per square inch); set the tire outdoors for one year; and then recheck the inflation pressure at room temperature after a one year period.

The tires were filled and deflated three times with nitrogen to purge the air out of the tire cavity. We also used an oxygen analyzer to be sure we had 95-percent nitrogen purity in the tire--the claimed purity limit of our nitrogen system, which generates nitrogen gas from ambient air.

The test started on September 20, 2006 and the final measurements were taken on September 20, 2007. The results show nitrogen does reduce pressure loss over time, but the reduction is only a 1.3 psi difference from air-filled tires. The average loss of air-filled tires was just 3.5 psi from the initial 30 pressure setting. Nitrogen-filled tires lost an average of 2.2 psi from the initial 30 psi setting. More important, all tires lost air pressure regardless of the inflation medium, so consumers should check their tires' air pressure routinely. No evaluation was done to assess the aging claim.

Bottom line: Overall, consumers can use nitrogen and might enjoy the slight improvement in air retention provided, but it's not a substitute for regular inflation checks.

CurtP

Consumer Reports is so out of touch with just about everything they do. Air retention isn't the main reason you use nitrogen. Nitrogen is dry, so pressures don't change as drastically as the tire temperature rises.

I see the need to use Nitrogen on aircraft tires (pressures in our MLG on the F/A-18 was 400psi when aboard a ship and we used nitrogen to charge the struts). I can even see it on a race vehicle. That being said, I see absolutely NO reason to run it on a street vehicle. I do, however, run a disposable coalescing filter on my air chuck to keep excessive moisture out of the tire.

Fox944

Curt, several street vehicles are equiped with Nitrogen from the factory. Nissan GTR's are one example. Nitro Fill was worth the money for me as it doesnt cost much. Air retention is better and pressure change is not nearly as drastic as you pointed out. I do a lot of spirited driving and also the occasional auto-x with my car. I'd rather use nitrogen in my tires as it doesnt cost much and is an upgrade.

edit: We actually fill the tires of every car sold with Nitro Fill (free of charge).

Damian in NJ

Planes do use nitrogen as they don't want any flammable 02 for safety issues, among other reasons. And since compressed air is almost 80% nitrogen anyway, and not all the other 20% of the gases are hydrophilic or have a large co-efficient of expansion, it's a bit of a sell on a street car. On a race car where you're dealing with fractions of a ppi in adjustments in pressure, I can totally see it.

It certainly can't hurt, though.

Fox944

It is benneficial and has zero drawbacks (other then costing more then 02). If you auto-x or track your car, it can be highly benneficial. Air Pressure can fluctuate several PSi btwn a few laps, thats not the case with Nitro and is one of the main reasons (among other things) it is used in race applications and standard from the factory on many ultra high performance cars.

FRporscheman

One of my tires leaks 1psi per day
so I check pressures all the time anyway

my poem for today.

Having my own air compressor in the garage, it's too easy to just keep all my tires filled with air. Especially since I change the pressure all the time, higher for the road trips to/from school, and lower for the backroad jaunts. N2 would be nice though.

SpeedBump

With 25-30 degree temp changes throughout the day I just shoot for a middle temp.