Tire Pressure & Adding Air
07-18-2012, 11:01 PM
#16
Registered User
The nitrogen thing may help with a nascar, or other special vehicle... but it's a waste of money in a passenger car. One of the car magazines, or it may have been consumer reports, did a test and after a year, the tire with air only lost 1.5 psi more than the nitrogen tire. Check your air pressure at least once a month and you'll be fine.
Even tire rack agrees... "Rather than pay extra for nitrogen, most drivers would be better off buying an accurate tire pressure gauge and checking and adjusting their tire pressures regularly."
Even tire rack agrees... "Rather than pay extra for nitrogen, most drivers would be better off buying an accurate tire pressure gauge and checking and adjusting their tire pressures regularly."
Also - the way I understand it - the primary benefit of Nitrogen is stability of tire pressure. In other words - pressure stays the same regardless of a 'cold' or 'warm' tire.
I still check my tires on a regular basis. I have not had to add anything to date. IF I did - the dealer simply told me to bring the car in - tell them I had to add air - and they would perform a purge/refill w/Nitrogen to spec.
Having said that - if I was asked to pay for it, I'd skip it!
Last edited by MalbecG37S; 07-18-2012 at 11:10 PM.
07-19-2012, 07:46 AM
#17
Also - the way I understand it - the primary benefit of Nitrogen is stability of tire pressure. In other words - pressure stays the same regardless of a 'cold' or 'warm' tire.
I still check my tires on a regular basis. I have not had to add anything to date. IF I did - the dealer simply told me to bring the car in - tell them I had to add air - and they would perform a purge/refill w/Nitrogen to spec.
I still check my tires on a regular basis. I have not had to add anything to date. IF I did - the dealer simply told me to bring the car in - tell them I had to add air - and they would perform a purge/refill w/Nitrogen to spec.
About purging/refill, i'm a little hesitant about how dealerships typically do it. They basically just let as much air as they can out, then fill with Nitrogen. There's no vaccum inside the tire when air is let out, so your Nitrogen fill post-purge is still contaminated.
Just something to think about. Bottom line is, as long as there's good pressure in there, it's all good.
07-19-2012, 08:18 AM
#18
Registered User
It's sort of true, but not entirely how people think it works. Nitrogen expands and contracts just like any other gas. The main reason NASCAR and other race teams use dry nitrogen is to rid the air of water content/moisture. It's the water that causes the changes in pressure. When you're racing at these speeds, even half a pound of pressure can make a big difference.
About purging/refill, i'm a little hesitant about how dealerships typically do it. They basically just let as much air as they can out, then fill with Nitrogen. There's no vaccum inside the tire when air is let out, so your Nitrogen fill post-purge is still contaminated.
Just something to think about. Bottom line is, as long as there's good pressure in there, it's all good.
About purging/refill, i'm a little hesitant about how dealerships typically do it. They basically just let as much air as they can out, then fill with Nitrogen. There's no vaccum inside the tire when air is let out, so your Nitrogen fill post-purge is still contaminated.
Just something to think about. Bottom line is, as long as there's good pressure in there, it's all good.
On the purge/refill - IF the dealership has a proper nitrogen 'station', it can run thru several purge/refills unattended - this is the best. IF it is some guy with his finger on the valve stem...not so good
07-19-2012, 09:49 AM
#20
Registered User
This is composition of air in percent by volume, at sea level at 15°C and 101325 Pa.
Nitrogen -- N2 -- 78.084%
Oxygen -- O2 -- 20.9476%
Argon -- Ar -- 0.934%
Carbon Dioxide -- CO2 -- 0.0314%
Neon -- Ne -- 0.001818%
A tire shop asked if I wanted nitrogen in my tires for a small fee, I said I'll take 78% nitrogen for free. He looked lost.
Nitrogen -- N2 -- 78.084%
Oxygen -- O2 -- 20.9476%
Argon -- Ar -- 0.934%
Carbon Dioxide -- CO2 -- 0.0314%
Neon -- Ne -- 0.001818%
A tire shop asked if I wanted nitrogen in my tires for a small fee, I said I'll take 78% nitrogen for free. He looked lost.
07-21-2012, 01:04 PM
#23
Here's a good excerpt from popular mechanics. Pretty much what everybody already touched on, but I thought it was still relevant.
There are several compelling reasons to use pure nitrogen in tires.
First is that nitrogen is less likely to migrate through tire rubber than is oxygen, which means that your tire pressures will remain more stable over the long term. Racers figured out pretty quickly that tires filled with nitrogen rather than air also exhibit less pressure change with temperature swings. That means more consistent inflation pressures during a race as the tires heat up. And when you're tweaking a race car's handling with half-psi changes, that's important.
Passenger cars can also benefit from the more stable pressures. But there's more: Humidity (water) is a Bad Thing to have inside a tire. Water, present as a vapor or even as a liquid in a tire, causes more of a pressure change with temperature swings than dry air does. It also promotes corrosion of the steel or aluminum rim.
If I ever need to top off a tire when I'm out on the road, I'll always briefly depress the tire chuck's valve with my thumbnail and vent some air. If my thumb gets wet, there's water in the line. Some gas stations don't do a very good job of keeping the humidity out of their air system. I don't even like to use a water-based tire-mounting lubricant unless I can let the tire bake in the sun for a couple of hours before I air it up and seat the bead. I've dismounted tires (not mine) that had several quarts of water inside—probably from a compressed-air hose that collected water and was never purged properly.
How is water relevant to a nitrogen discussion? Any system that delivers pure nitrogen is also going to deliver dry nitrogen. Filling tires with nitrogen involves filling and purging several times in succession, serially diluting the concentration of oxygen in the tire. This will also remove any water.
It's certainly simple, although time-consuming, for a tire technician to fill and bleed tires. But most shops use a machine that not only generates almost pure nitrogen by straining the oxygen out of shop-compressed air, but will also automatically go through several purge cycles unattended. Some shops have been charging as much as $30 per tire for this service. I think that's too much. If you're buying a new tire, it should be far less. Still, the nitrogen generator, filling system and technician's time aren't free—the dealer is entitled to some return for that.
So, to answer your specific questions: With nitrogen, your tire pressures will remain more constant, saving you a small amount in fuel and tire-maintenance costs. There will be less moisture inside your tires, meaning less corrosion on your wheels. You will not be able to feel any difference in the ride or handling or braking, unless your tire pressures were seriously out of spec and changing to nitrogen brought them back to the proper numbers.
There are several compelling reasons to use pure nitrogen in tires.
First is that nitrogen is less likely to migrate through tire rubber than is oxygen, which means that your tire pressures will remain more stable over the long term. Racers figured out pretty quickly that tires filled with nitrogen rather than air also exhibit less pressure change with temperature swings. That means more consistent inflation pressures during a race as the tires heat up. And when you're tweaking a race car's handling with half-psi changes, that's important.
Passenger cars can also benefit from the more stable pressures. But there's more: Humidity (water) is a Bad Thing to have inside a tire. Water, present as a vapor or even as a liquid in a tire, causes more of a pressure change with temperature swings than dry air does. It also promotes corrosion of the steel or aluminum rim.
If I ever need to top off a tire when I'm out on the road, I'll always briefly depress the tire chuck's valve with my thumbnail and vent some air. If my thumb gets wet, there's water in the line. Some gas stations don't do a very good job of keeping the humidity out of their air system. I don't even like to use a water-based tire-mounting lubricant unless I can let the tire bake in the sun for a couple of hours before I air it up and seat the bead. I've dismounted tires (not mine) that had several quarts of water inside—probably from a compressed-air hose that collected water and was never purged properly.
How is water relevant to a nitrogen discussion? Any system that delivers pure nitrogen is also going to deliver dry nitrogen. Filling tires with nitrogen involves filling and purging several times in succession, serially diluting the concentration of oxygen in the tire. This will also remove any water.
It's certainly simple, although time-consuming, for a tire technician to fill and bleed tires. But most shops use a machine that not only generates almost pure nitrogen by straining the oxygen out of shop-compressed air, but will also automatically go through several purge cycles unattended. Some shops have been charging as much as $30 per tire for this service. I think that's too much. If you're buying a new tire, it should be far less. Still, the nitrogen generator, filling system and technician's time aren't free—the dealer is entitled to some return for that.
So, to answer your specific questions: With nitrogen, your tire pressures will remain more constant, saving you a small amount in fuel and tire-maintenance costs. There will be less moisture inside your tires, meaning less corrosion on your wheels. You will not be able to feel any difference in the ride or handling or braking, unless your tire pressures were seriously out of spec and changing to nitrogen brought them back to the proper numbers.
07-21-2012, 10:50 PM
#24
This is composition of air in percent by volume, at sea level at 15°C and 101325 Pa.
Nitrogen -- N2 -- 78.084%
Oxygen -- O2 -- 20.9476%
Argon -- Ar -- 0.934%
Carbon Dioxide -- CO2 -- 0.0314%
Neon -- Ne -- 0.001818%
A tire shop asked if I wanted nitrogen in my tires for a small fee, I said I'll take 78% nitrogen for free. He looked lost.
Nitrogen -- N2 -- 78.084%
Oxygen -- O2 -- 20.9476%
Argon -- Ar -- 0.934%
Carbon Dioxide -- CO2 -- 0.0314%
Neon -- Ne -- 0.001818%
A tire shop asked if I wanted nitrogen in my tires for a small fee, I said I'll take 78% nitrogen for free. He looked lost.
07-22-2012, 07:21 PM
#25
Don't forget that the more important part is the purging of the moisture in the tire that counts. This moisture is what causes all the air pressure fluctuations during use. I doubt it's of much concern for corrosion on the rims since most of the rims are painted on the inside and out. The European spec. rims must be painted because of their stricter regulations and to also reduce corrosion and possible bleed through the pores of the rims. Magnesium rims are the worst offenders in that area.
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