| Author | Message | ||
     Banana_man |
recently had some new tyres fitted to my bike and the company that fitted them filled them up with nitrogen. I asked them what pressures he had filled them up to and he said he had taken them to the standard pressures. now this is my quanderey. I was always under the impression that "air" expanded as the tyre got hot and increased the pressure in the tyre. So when you fill the tyre with nitrogen " that does not expand with heat" you had to increase the preasure in your tyre to compensate for the tyre pressure not increasing. When I said this to the guy he said that the manufacturers do not take this into account.so the tyre pressures run high during everyday use. I beleive he is talking b*^^0cks but wanted to ask you guys what your thoughts are on the subject. Is there any of you in the now! if so , by how much should you alter the pressures from standard (if any) and in what direction? cheers | ||
| Xodot |
Going back to high school physics, all gas expands as it gets hot and that includes nitrogen. The difference in the expansion of air and nitrogen will not be noticeable. IMHO - you have a non-issue here | ||
| Zane_t |
In racing applications, tires do run cooler and it has been proven that pressures do not increase as much when inflated with nitrogen vs air. Being a denser gas than air, which is a mix of nitrogen, oxygen, CO2 and argon, the other advantage is not having to check the pressure as often, because it doesn't seep out as fast. For everyday riding, I wouldn't worry about altering the pressures, and when in doubt, just use air. For street riding, there really is no advantage to using nitrogen as long as you check your pressures like you should. | ||
| Duphuckincati |
Yeah, what he said! | ||
| Slaughter |
Not exactly. Compressed air with normal/expected presence of WATER will expand more than the same volume of a DRY GAS. SCUBA air (also thoroughly dry) will give the same effect. Remember, what you breathe is 78% nitrogen already. (Message edited by slaughter on July 04, 2010) | ||
| Datsaxman |
BTW, Nitrogen (or air) only expands enough for a pressure increase of a few PSI at the track. So the expansion is small on the street for sure. Nitrogen expands. All gases, when treated as "ideal gases" expand similarly. Safe to think of any gas as an ideal gas below about 5 times atmospheric pressure. The difference between Nitrogen and air is TINY on the street, and almost entirely due to the water in ordinary air. | ||
| Usanigel |
Run stock pressure and set cold (not ridden for 60 Min's) the small amount of difference from street riding will not be noticed. When hot the tire pressure will increase about 10%. | ||
| Slaughter |
Couple things at work here - air contains almost 1% water... keep in mind that as STEAM water can expand up to 1600 times its original volume. DRY AIR or Nitrogen will do pretty much the same thing for you. Now you know why racers tend to measure tire pressures HOT. That'll work when using air, nitrogen, or any other gas. What matters is the performance of the tire carcass and tread when it's up to temperature. Air compressors typically do NOT dry the air so compressed air DOES expand more when being heated than nitrogen or dry air. | ||
| Banana_man |
thanks for the feedback guys. I'm going to fill up with air from now on cheers Kev |
