NITROGEN FOR YOUR TYRES
IT'S ALL RIGHT NOW
IN FACT IT'S A GAS
by Brother Silverback
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Ubercoool 2006: a tyre pump with an ignition key... |
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The Airtec machine correctly diagnosed Brother Silverback's handling problem: his bike had one wheel too many |
No, not NOS for your motor, but nitrogen for your tyres. What is commonplace but not de rigeur for the Moto GP is the substitution of air with nitrogen in both tyres. I have for the last 15,000 kms used this system in Metzler's Racetec fitted to my BMW K1200R and being so impressed with it, have done the same on the same rubber now fitted to my Aprilia Tuono R.
I was talked into giving this a try by Luke Macrae, previously of Procycles Tyre Centre at Hornsby and what originally took my fancy was my own thinking, (probably fallacious), that given the tyres don't heat up internally as much as air inflated tyres, the memory cycles for each tyre would not be used up as quickly, thus allowing me to run stickier tyres. Thus I went to Metzeler Racetecs, #1 on the front and #2 on the rear, (and up to a 55 instead of a 50 on the K12, which has dramatically improved the handling -- but that it is another story).
There is another purpose for thinking about using nitrogen and that is that nitrogen avoids loss of pressure at the same rate as air, which loses oxygen permeating through the tyre wall. Using nitrogen reduces the loss of pressure, so although you still need to check your tyres' pressures, instead of each week, the pressure will stay consistent for six to eight weeks. I've found that over an eight-week period, regardless of how much or how little the bike is ridden, the pressure loss has been 2 lbs per 8 weeks.
Of course, there is one difficulty with nitrogen and that is that you have to return to the installer to check, purify and top up the nitrogen in each of the tyres, which may not be convenient for those in the country. I live reasonably close to Hornsby, where Procycles provide this service, so it is not inconvenient for me. By the way, the purity of nitrogen in your tyre should be over 96% to obtain the benefits and mine have so far have been maintained at 98%.
The formal guff on nitrogen, which seems to be the case, is that tyres filled with nitrogen provide a larger contact patch with the road resulting in less tyre wear due to the fact that nitrogen reaches operating pressure and then stabilises. Normal air contains water molecules that expand rapidly when heated causing the tyre to over-inflate reducing the contact patch and available grip. That's why you drop your tyre pressures considerably when you go to the track. With the K12, the Sportec M1s I was running wore out in about 4,000kms and the Racetecs filled with nitrogen were still doing ok at 7,500kms plus, until I scored a nail in the back tyre. Furthermore, there is no need to drop the pressures at the track. In emergency situations, one can fill the tyre up with air and run it as per normal, as I did when I got a puncture. Then if you still want to continue using the same tyre after repair or after replacing a faulty valve, the nitro tyre people replace the air with nitrogen and everything is back to the improved normal.
There is not an issue with the warm up time either. The surface temperature of the tyre is not affected by the cooler internal temperature of a nitrogen filled tyre. Therefore, the warm up time for the carcass is the same as for an air filled tyre.
The other advantage I've found is with the more constant retained air pressure, particularly with a bike that is not used every day. When the Aprilia had been sitting during the working week, I found that it usually lost about 2 lbs of pressure each fortnight or so, but since putting in the nitrogen, the pressure has been maintained for three times that period. Certainly an advantage for those that have a bike that is not used every day.
If you are close to a shop that provides this facility, I would certainly recommend that you give it a try. There is no issue that you will increase dramatically your tyre life, but also, I am of the view, that you can run more track orientated tyres on the street, without the tyre going off, before you've worn the tread out. That's got to be a good thing, particularly for those who use their bike both on the street and at the track.
