Nitrogen versus air

[tannat]

So I've had my Focus for 3 years + and about 44k miles. A few track days- I feel i know thee car pretty well.

Until the most recent set of tires (replaced at 38k) all tires have been filled with compressed air.

The current set has nitrogen. I had these tires installed in the spring when temps were in the high 20s (Celsius). Recently temps have dropped significantly (as well as humidity). Now the car bounces like a rubber ball after hitting a bump. Its a bit unsettling and reall hurts the 'seat of pants' feel of the car.

Granted-it could be any number of other factors (suspension, driver, etc) and I have considered these, but Occam's razor points to the nitrogen.

Has anyone else experienced a similar phenomenon with nitrogen filled tires and drops in temps?

[Zico]

Nothing to do with grip levels then? Sounds like the dampers to me.
Nitrogen is obviously far more stable than air, the water content will be far lower and the pressures dont fall as much when the temperatures drop... but Isn't a lower tyre pressure what you want when the ambient temps drop? I know I always drop my tyre pressures a couple of PSI over the winter months.

There is an interesting thread on the subject here.. http://www.ten-tenths.com/forum/showthread.php?t=119666&highlight=nitrogen

[tannat]

Cheers Zico. Thanks.

I plan to give it the car a good hard look this weekend...

[Daniel]

Why would you drop pressures in the winter?

[Zico]

Why would you drop pressures in the winter?

With normal garage forecourt air, tyre pressures drop by 1 PSI for every 10 deg drop in temp.

I also always make sure my tyres are set a couple of PSI lower in the winter anyway, its not only cold but wet 90% of the time here, If I keep them at summer (F34-R32 PSI) pressures I find the car much more nervous, less comunicative and the grip much less progressive, probably to do with the increased tyre roll suiting the lower grip levels better. Does no one else find that?

[Easy Drifter]

Nitrogen is far less affected by temp. than compressed air.
Unless you have a leak(s) there should be no noticable difference in handling with a drop in temp.
I would, of course, check presssures but I suspect your problem is elsewhere.
As suggested quite likely shocks. Worn bushings in the sway bar links or control arms are another possiblity. As you have used the car in limited competition plus age these are distinct possibilities.
But shocks are most likely.
AKA Dampers

[Hondo]

Lower tire pressure does give you more traction, grip, and feel. Check out the air pressures on the tires of a trials motorcycle. They run just enough to keep the tire on the rim.

[janneppi]

Why would you drop pressures in the winter?
From what I've heard it's the opposite, as pressure in tyres drops in colder climate, you need to counter it. If you have 2.2 bar at 20C , it drops to 2.0 bar at 0C.

[Daniel]

With normal garage forecourt air, tyre pressures drop by 1 PSI for every 10 deg drop in temp.

I also always make sure my tyres are set a couple of PSI lower in the winter anyway, its not only cold but wet 90% of the time here, If I keep them at summer (F34-R32 PSI) pressures I find the car much more nervous, less comunicative and the grip much less progressive, probably to do with the increased tyre roll suiting the lower grip levels better. Does no one else find that?

I really don't agree with that at all.

You will always want the same pressure (when cold) in your tyres regardless of temperature.

In the snow you definitely don't want tyres which are narrower because it'll be harder for them to bite down. You also don't want a wider tyre in the wet either because a narrower tyre will displace water better.

I'd be very sceptical about anything in that thread, there's a lot of crapola in there like that nitrogen inflated tyres lose pressure more quickly because nitrogen molecules are smaller than oxygen molcules which is rubbish.

http://www.theaa.com/motoring_advice/safety/filling-tyres-with-nitrogen.html

As for the OP, I'd check the car out. That said is it possible you're just feeling a reduction in lateral grip? I find the Fiat bouncier around certain corners when it's colder.

[tannat]

Nitrogen is far less affected by temp. than compressed air.
Unless you have a leak(s) there should be no noticable difference in handling with a drop in temp.
I would, of course, check presssures but I suspect your problem is elsewhere.
As suggested quite likely shocks. Worn bushings in the sway bar links or control arms are another possiblity. As you have used the car in limited competition plus age these are distinct possibilities.
But shocks are most likely.
AKA Dampers

I'll have a check, ED, but she's a young car, and limted track use, but who knows..

We give me an excuse to upgrade the shocks :up:

[Zico]

From what I've heard it's the opposite, as pressure in tyres drops in colder climate, you need to counter it. If you have 2.2 bar at 20C , it drops to 2.0 bar at 0C.

Unless you have wet winters with slimy salted roads like we do, then 2.0 bar should be better, especially have you have a sensitive and sporty car.


I really don't agree with that at all.

You will always want the same pressure (when cold) in your tyres regardless of temperature.

In the snow you definitely don't want tyres which are narrower because it'll be harder for them to bite down. You also don't want a wider tyre in the wet either because a narrower tyre will displace water better.

I'd be very sceptical about anything in that thread, there's a lot of crapola in there like that nitrogen inflated tyres lose pressure more quickly because nitrogen molecules are smaller than oxygen molcules which is rubbish.

http://www.theaa.com/motoring_advice/safety/filling-tyres-with-nitrogen.html

As for the OP, I'd check the car out. That said is it possible you're just feeling a reduction in lateral grip? I find the Fiat bouncier around certain corners when it's colder.

As I said, we have cold wet winters with slimy salted roads so grip levels are even lower than with just a mere rain shower. You may not believe me but I notice a difference, the grip falls off more progresively with even just a couple of PSI less pressure.

[janneppi]

Unless you have wet winters with slimy salted roads like we do, then 2.0 bar should be better, especially have you have a sensitive and sporty car.

I switch to studded tyres usually around late October / early November. ;) The car is neither sporty nor sensitive with those rubbers. :p :

[ioan]

From what I've heard it's the opposite, as pressure in tyres drops in colder climate, you need to counter it. If you have 2.2 bar at 20C , it drops to 2.0 bar at 0C.

Exactly.

[ioan]

Lower tire pressure does give you more traction, grip, and feel.

And much less precision, which isn't really better no matter how much more traction you might get with less pressure.

IMO what one needs to do is to keep the pressure at the levels that are prescribed by the tire manufacturer, they know best what are the right numbers!

[Daniel]

Unless you have wet winters with slimy salted roads like we do, then 2.0 bar should be better, especially have you have a sensitive and sporty car.



As I said, we have cold wet winters with slimy salted roads so grip levels are even lower than with just a mere rain shower. You may not believe me but I notice a difference, the grip falls off more progresively with even just a couple of PSI less pressure.
I really don't agree that simply dropping the pressures down will give more grip in winter.

Lets see what Donkey Jote says ;) If anyone is best equipped to comment, it's him.

[Zico]

I really don't agree that simply dropping the pressures down will give more grip in winter.

Lets see what Donkey Jote says ;) If anyone is best equipped to comment, it's him.

I didn't say it gives you more grip, it just enables you to feel when you are reaching the lower grip limits, more comunication and less nervous.

There seems to be a lot of conflicting theories about this judging from this tyre temps vs tyre pressures thread http://www.ten-tenths.com/forum/showthread.php?t=43078&page=2 I guess there are so many variables that what works for some might not for others but it works for me.

[Daniel]

I didn't say it gives you more grip, it just enables you to feel when you are reaching the lower grip limits, more comunication and less nervous.

There seems to be a lot of conflicting theories about this judging from this tyre temps vs tyre pressures thread http://www.ten-tenths.com/forum/showthread.php?t=43078&page=2 I guess there are so many variables that what works for some might not for others but it works for me.

Excuse me if I don't exactly find what they're saying convincing. I'll wait for Donkey Jote to give his 2 euro cents ;)

[Azumanga Davo]

I've only ever seen one road car here with nitrogen in the tyres (it was from Queensland and had green valve caps). The bloke asked me if I knew where the nearest place he could get nitrogen for them as they leaked a bit. I didn't have a clue if that was a normal service extra or whatever, wonder if he ever did find a place...

[Zico]

After a bit of thought about this... I wouldn't junk these dampers just yet Tannat, damper fluid is going to increase in viscosity as the temps fall right?

I fitted adjustable AVO's to my GTI and spent a fair amount of time experimenting with the variable settings, when I stiffened them right up the car was great fun to drive.. much more chuckable but it litterally bounced round the corners, chuckable and fun but definately not fast. If you do ever get new dampers stay away from adjustables or at least AVO's in particular.. I only got about 10k miles from them before 2 developed a leak, that said... I did give them a bit of punishment to be fair.

[airshifter]

I've noticed on quite a few cars that initial ride quality is down in the cold weather. I've always assumed it was due to cold dampers, cooler tire temps, etc.

As for pressures vs handling and grip levels, it's apparent to me that lower tire pressures present a larger contact patch and more grip, but at the same time the sidewall is not as stiff and the tire might not feel as solid. Unless you air a tire way down the contact patch really never gets wider, but it gets longer even with lesser pressure changes.

[Easy Drifter]

Wait till it is -30 to -40. Nothing wants to work. Gears do not want to change. Springs and shocks are solid. Speedo goes nuts. Shows 180k in first gear!!!!! Tire sidewalls are solid and tires feel square. Even the seat springs don't really work. At first it is like sitting on a very cold board.
After a few miles things warm up and start to work normally. :D

[tannat]

After a bit of thought about this... I wouldn't junk these dampers just yet Tannat, damper fluid is going to increase in viscosity as the temps fall right?

Gave the dampers a few shoves this PM-they seem solid. I think they are fine.

I'm going to cross check my pressure gauge and make sure its correct, and check pressures of course.

After a chilly day tomorrow temps get spring like agin next week. It will bbe interesting to see if the problem disappears...

[Daniel]

Still waiting for donks to see the thread :P

[Daniel]

Still waiting for donks to see the thread :P

[schmenke]

Wait till it is -30 to -40. Nothing wants to work. Gears do not want to change. Springs and shocks are solid. Speedo goes nuts. Shows 180k in first gear!!!!! Tire sidewalls are solid and tires feel square. Even the seat springs don't really work. At first it is like sitting on a very cold board.
After a few miles things warm up and start to work normally. :D

:D

[donKey jote]

Still waiting for donks to see the thread :P

personally I'd fill them with liquid helium. Not sure it'd do any good but it's always good for a laugh :)

[tannat]

personally I'd fill them with liquid helium. Not sure it'd do any good but it's always good for a laugh :)


:p :D

[Daniel]

What's your opinion on changing pressures during winter donks?

[donKey jote]

I add air when the pressure is below the recommended values regardless of winter or summer. :)

[ioan]

I add air when the pressure is below the recommended values regardless of winter or summer. :)

C'mon man, this is corporate brainwash! :p

Just joking! I fully agree with you.

[donKey jote]

C'mon man, this is corporate brainwash! :p
btw are you using winter tyres yet ? :p

[ioan]

btw are you using winter tyres yet ? :p

Yep, with 18 degrees outside last week I was a bit sorry for them, law has to be respected, and also the corporate policy for the corporate car needs to be respected.

[donKey jote]

I'm changing mine tomorrow. It's now 0°-4° here :s .
I'll be filling them with 78% Nitrogen and a mix of other gases, to ~2.0 bar cold :D

[schmenke]

Still on summers here :wave:
Although the temps are gradually falling, the long-term forecast is for dry weather. This may turn out to be the latest that I've ever done the swap.

And I'll likely use the same mixture as donks :p : .

[Easy Drifter]

Still on my worn out No Weather Contis.
Thinking about these new Hanhook tires with summer tread on outside, all weather centre and winter inside edge.
Interesting concept but I expect there will be uneven wear pattern.
Note just thinking!

[Daniel]

I'm on winters as of Saturday. 4 degrees and wet today, no wheelspin, yay!!!!!

[schmenke]

...
Thinking about these new Hanhook tires with summer tread on outside, all weather centre and winter inside edge.
Interesting concept but I expect there will be uneven wear pattern.
Note just thinking!

The missus's SUV has been fitted with similar Good Year Fortenzas for a few years now. They work well in snowy/icy conditions, but the AWD probably contributes more than the tires themselves :mark: . No noticable uneven wear patterns on them.

[ioan]

I'm changing mine tomorrow. It's now 0°-4° here :s .
I'll be filling them with 78% Nitrogen and a mix of other gases, to ~2.0 bar cold :D

We had 0° when I changed them however 3 days later it was up to 15°, go figure.

I've also heard that the mix 78% N and 21° O2, a bit of CO2 and some extra is a good one, and also dirt cheap (for now at least). ;)

[Rollo]

I thought that the point of Nitrogen gas in tyres was that N2 is a physically bigger chemical that most of the other constituents of air (like O2 which is smaller), and that because N2 is larger it doesn't seep out through the tyre walls and valves as much.

I made a point of checking the pressures on the Ka when I filled the tank, which was weekly. They typically ran between 40psi and 43psi, to cut down on rolling resistance and therefore increase fuel economy.

My wife's Skyline is an altogether bouncier car which runs all four tyres at 32psi without fail. Nissan recommends 28psi and Goodyear recommends 32psi, and I'm more inclined to follow the tyre company because they're tyre specialists whereas Nissan wants to give you a kinder ride.

[Zico]

I thought that the point of Nitrogen gas in tyres was that N2 is a physically bigger chemical that most of the other constituents of air (like O2 which is smaller), and that because N2 is larger it doesn't seep out through the tyre walls and valves as much.

Although what you say is true, the reason as actually one of temperature stability where the PSI isn't affected as much by the tyre temps.

Daniel,

"the pressure inside the tire affects friction and therefore performance. Pressure is determined by the characteristics of the tyre, weight of vehicle and circuit layout. Pressure affects both grip and consistancy of the tyre, it should be at a minimum to get the maximum area of rubber on the ground but high enough to minimise heat generation by tyre deformation and keep the tyre bead seated on the rim.."

http://www.bridgestonemotorsport.com/Bridgestone/tyre-technology/glossary.html

On a slimy salted road where the grip is even lower than a mere wet surface, that lower grip stops the tyre rolling/deforming where it would on higher grip surfaces.
Yes as Ioan says , reducing the tyre pressure makes the steering a tad less direct (only 2 PSI remember) but that tiny pay-off is still more than worth it for the advantages it brings, just my own findings.

[janneppi]

I'm not at all sure I'd be able to spot any difference car handling or grip level in a blind test if the difference was about 2 psi. :)

[Zico]

I'm not at all sure I'd be able to spot any difference car handling or grip level in a blind test if the difference was about 2 psi. :)

I would have thought the same but It definately does feel better. I guess it depends on the many variables there are, what you drive, its weight, the tyre construction etc etc.
Some cars are a lot more 'wired' as far as driver feedback goes than others. I just seem to find better traction and the cornering grip falls away more progressively, less knife edge... which makes it less nervous.

[Easy Drifter]

Quite a while ago now but we adjusted tire pressures on racing tires by a 1/4 lb. and there was a difference in handling. The max. reading on the gauge we used was 30 lb. We ran around 13 to 14 lb range on both Goodyears and Hoosier.
Earlier with Firestones about 15 to 17 lb.
Admittedly different than street use