Stock rubber mileage

[root]

I have a hard time believing that nitrogen makes any real difference. Somebody got it in their head that since nitrogen is used in aircraft tires it must be good for motorcycles, too. Jet fighters! 
Aircraft use pure nitrogen because it's dry. Regular atmospheric air contains moisture which freezes at high altitudes. But unless you routinely ride at 30,000 feet, this shouldn't be an issue.
 
This reminds me of the company a few years ago that tried to sell motorcycle retreads on the basis that "jet fighters use retreads!" LOL. Yeah they do, and they fall apart on jet fighters all the damn time.

The real good thing about Nitrogen is the size of it's molecules. They are larger than air so they do not pass through the tires as easily, and subsequently retain the air pressure longer. linky1 linky2
linky3

I call snake oil salesman on that one.  Even if it were true (which I still don't think it is), with 78 percent of air being nitrogen, after a 12% loss it would stablilize at 78%.  The tire would then be 100% Nitrogen at 78% capacity.  New air would be put in with 78% nitrogen leaving less than 5% of the air being oxygen / other gasses.  By the third time of adding air you would have ~99.8% nitrogen. 
There's real benefits to nitrogen in a lot of applications.  Molecule size is not one of them IMHO.  The biggest benefits to nitrogen come because it's dry.  I'm not convinced those benefits manifest themselves on a sport touring motorcycle.  Racing? yes.  Extreme cold? yes.  60-90 deg cruising weather? Probably not so much.

[skipperT]

The real good thing about Nitrogen is the size of it's molecules. They are larger than air so they do not pass through the tires as easily, and subsequently retain the air pressure longer. linky1 linky2
linky3

I call snake oil salesman on that one.  Even if it were true (which I still don't think it is), with 78 percent of air being nitrogen, after a 12% loss it would stablilize at 78%.  The tire would then be 100% Nitrogen at 78% capacity.  New air would be put in with 78% nitrogen leaving less than 5% of the air being oxygen / other gasses.  By the third time of adding air you would have ~99.8% nitrogen. 
There's real benefits to nitrogen in a lot of applications.  Molecule size is not one of them IMHO.  The biggest benefits to nitrogen come because it's dry.  I'm not convinced those benefits manifest themselves on a sport touring motorcycle.  Racing? yes.  Extreme cold? yes.  60-90 deg cruising weather? Probably not so much.

 
 
Thanks for all the math. But my point is simply that the tires don't lose pressure over a period of time like they do with air. Thats what I observed.
 
YMMV

-S

[oldfart]

Not that I'm EVER going to put nitrogen in my bike tires, because I'm not, but I would wonder if nitro affects the running temperature of the tires, which could affect grip. But then again, quite honestly, I have no idea what I'm talking about, haha.

[wessie]

Not that I'm EVER going to put nitrogen in my bike tires, because I'm not, but I would wonder if nitro affects the running temperature of the tires, which could affect grip. But then again, quite honestly, I have no idea what I'm talking about, haha.

on a race track it may give you an advantage over competitors who have the same ambient temperature, road surface temperature and control tyres. 
in a road application I cannot believe you would detect the difference as you will always have varying grip on public roads due to the effects of wear, rubber & fuel deposits, ambient temperature, moisture, sunlight, roadkill and gravel on the surface. 

[ULEWZ]

Not that I'm EVER going to put nitrogen in my bike tires, because I'm not, but I would wonder if nitro affects the running temperature of the tires, which could affect grip. But then again, quite honestly, I have no idea what I'm talking about, haha.

Gleaned from Edmonds.com: Better tire-pressure retention: Over time, a tire will gradually lose pressure. Changes in temperature will accelerate this. The general rule of thumb is a loss of 1 psi for every 10-degree rise or fall in temperature. The institute says that nitrogen has a more stable pressure, since it has larger molecules than oxygen that are less likely to seep through the permeable tire walls.
 
In 2006, Consumer Reports conducted a year-long study to determine how much air loss was experienced in tires filled with nitrogen versus those filled with air. The results showed that nitrogen did reduce pressure loss over time, but it was only a 1.3 psi difference from air-filled tires. Among 31 pairs of tires, the average loss of air-filled tires was 3.5 psi from the initial 30 psi setting. Nitrogen-filled tires lost an average of 2.2 psi from the initial setting. Nitrogen won the test, but not by a significant margin.
Improved fuel economy: The EPA says that under-inflated tires can lower gas mileage by 0.3 percent for every 1 psi drop in pressure of all four tires. The theory is that since nitrogen loses pressure at a slower rate than air, you are more likely to be at the correct psi and therefore get better fuel economy.
 
If you are proactive and check your tire pressure at least once a month, you can offset this difference with free air, and you won't need expensive nitrogen. We think this invalidates the "better fuel economy with nitrogen" argument.
 
For many people, however, this kind of maintenance is easier said than done. Most people either forget to regularly check and top off their tires, or never learned how to do it in the first place. Even Edmunds employees (typically a pretty car-savvy group) were under-inflating or over-inflating their tires, according to a tire-pressure study we conducted a few years ago.
 
And though tire-pressure monitoring systems (TPMS) now come standard on cars, a 2009 National Highway Transportation Safety Administration (NHTSA) study found that only 57 percent of vehicles with TPMS had the correct tire pressure. That's because most systems are only meant to signal that a tire has very low pressure, not to show that the pressure is optimal.
Cooler running temperatures: When air is pressurized, the humidity in it condenses to a liquid and collects in the air storage tank you use at the local gas station. When you add compressed air to the tire, the water comes along for the ride. As the tire heats up during driving, that water changes to a gas, which then expands, increasing tire pressure. Because nitrogen is dry, there is no water in the tire to contribute to pressure fluctuations.
 
But this fluctuation in temperature isn't as significant as you might think. A 2008 ExxonMobil study plotted the changes in temperature over the course of various inflation pressures. The lines on the graph were virtually on top of each other. In other words, the change in temperature when using nitrogen was negligible.
Prevent wheel rot: Nitrogen proponents will also point out that water in a tire can lead to wheel rot. A tire engineer who anonymously maintains Barry's Tire Tech, a blog on a number of tire issues, says this isn't really a problem with modern cars.
 
"Alloy wheels don't really have a problem with water inside the tire," the engineer writes in a post on nitrogen inflation. "They are coated to keep aluminum from forming aluminum oxide, which forms a crust, which isn't very attractive. But even then, this crust protects the aluminum from further corrosion from the water."
 
Where wheels have problems is when the aluminum alloy contacts steel, such as the steel spring clip used on wheel weights. It's a particular issue when salt is present, the engineer writes. "But this problem is totally independent of the inflation gas," he says. "Steel wheels only have a problem if the paint is damaged."
 

[builderbob]

This has gotten quite interesting. Carry on.

[root]

I call snake oil salesman on that one.  Even if it were true (which I still don't think it is), with 78 percent of air being nitrogen, after a 12% loss it would stablilize at 78%.  The tire would then be 100% Nitrogen at 78% capacity.  New air would be put in with 78% nitrogen leaving less than 5% of the air being oxygen / other gasses.  By the third time of adding air you would have ~99.8% nitrogen. 
There's real benefits to nitrogen in a lot of applications.  Molecule size is not one of them IMHO.  The biggest benefits to nitrogen come because it's dry.  I'm not convinced those benefits manifest themselves on a sport touring motorcycle.  Racing? yes.  Extreme cold? yes.  60-90 deg cruising weather? Probably not so much.

Thanks for all the math. But my point is simply that the tires don't lose pressure over a period of time like they do with air. Thats what I observed.
 
YMMV

-S

 
I have observed very similar results with regular air in some tires. Other tires not so similar results. I just think there are more variables than molecule size that make bigger differences. Otherwise you would observe losses on all tires at a similar rate with regular air and after the 3rd fill with regular air you would be at a higher percentage of nitrogen than a nitrogen filled tire. A tire filled with nitrogen is still capable of losing pressure, so you still have to check it. If you can get nitrogen fill ups for free, it's clearly better. I'm not trying to say you shouldn't do it. But given I would still need to check my tires regularly and I have a compressor in my garage, I can't really justify spending any extra money on nitrogen for daily use given the minimal benefits for this specific application.

[lamwayne]

Mine look like this after 9200km of commuting.  The rear probably has 2-3000km left and the front has at least 5000km.  
 

 

 

 

[lunchbox]

I got about 4K on the rear, at which time I swapped them out for a set of B'stone T-30s (got a great deal on them). I found the D222 to be a much better tire than the T-30, but I can't speak to longevity of the latter just yet. My next set will most likely be PR4s.

[johan]

I erred on the side of caution and changed the rear at around 3500 before going to France. Based on the wear on @johan's tyre on the same trip, I think I could have used the D222 for the trip. @johan went on to get over 7000 miles out of his rear tyre, mostly commuting miles. 
The advantage for me was that I did not have any of that will it, won't it last anxiety for my holiday.

The wear rate was interesting Wessie, the first 3,000 miles or so seemed to take a lot off it, but after that it began to wear more evenly. To be accurate, I changed the tyre on the day before my second service at 6,300 odd miles. I was almost on the wear bars and I could feel the tyre squirm when I leaned over. The new tyre feels subjectively, as new tyres do, much better and more positive on turn in. I've not even scrubbed it though, as I went on vacation to France two days after I had it fitted.

[vince]

3k miles and the leading edge of all side tread is gone on the rear.
Still lots left in the center.
Guess I need to take some trips and lighten up on the twisties?

[wessie]

I erred on the side of caution and changed the rear at around 3500 before going to France. Based on the wear on @johan's tyre on the same trip, I think I could have used the D222 for the trip. @johan went on to get over 7000 miles out of his rear tyre, mostly commuting miles. 
The advantage for me was that I did not have any of that will it, won't it last anxiety for my holiday.

The wear rate was interesting Wessie, the first 3,000 miles or so seemed to take a lot off it, but after that it began to wear more evenly. To be accurate, I changed the tyre on the day before my second service at 6,300 odd miles. I was almost on the wear bars and I could feel the tyre squirm when I leaned over. The new tyre feels subjectively, as new tyres do, much better and more positive on turn in. I've not even scrubbed it though, as I went on vacation to France two days after I had it fitted.

 
Our usage is very different as well. Your main accumulation of mileage is commuting into the centre of London.. I imagine a lot of this is stop-start riding from one set of traffic lights to another. Your roads are mostly surfaced with asphalt. My mileage is largely from leisure use on rural roads in A mode. Most of these roads are surface dressed with granite chips and I'm accelerating out of the corners with enthusiasm. A combination of a higher percentage of miles accelerating in A mode and the very abrasive nature of granite chips is my theory of how I had little confidence in the tyre lasting much beyond 4000 miles and you can get 6000 miles from a rear D222.

[skipperT]

Mine look like this after 9200km of commuting.  The rear probably has 2-3000km left and the front has at least 5000km.   

 
 
Wow, you get a way nicer key than we do in the 'states!
 
Skip

[wessie]

My key is like that. I guess voodoo in Hong Kong gets the immobiliser that we get in Europe (also reported as a successful theft deterrent by an Australian). The key is fitted with a passive transponder which pairs with the immobiliser to activate the ignition.

[lamwayne]

SkipperT,
 
Yes, the key has an immobilizer chip inside.