BMW K bikes (Bricks)

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roys

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Hi,

I'de appreciate any opinion on the issue of what is the right tyre pressure for a hot dry climate where there is no rain for 9 mo. of the year and summer temps are around 100 and the asphalt burns.

Somehow I get the idea BMW designed this bike, perhaps Subconsciously for cooler european and north american climates (re the engine heat issue on rider).

Roy

    

K-BIKE

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Personally I would use the pressures recommended by BMW and the tyre manufacturers UNLESS you are prepared to undertake a development program with thermal imaging and measurement across the tyre tread under running conditions at varying pressures to determine the optimum pressure.
Regards,
K-Bike

    

roys

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thank you
that was very clear
Roy

    

K-BIKE

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Hi Roy,
I realised on reading my response it appears abrupt and dismissive which was not intended. I was in a rush so did not reply with the full detail I had in mind. What I wanted to do was put in the following very useful piece of info from Fluke the manufacturer of excellent measuring equipment. http://www.coleparmer.com/techinfo/techinfo.asp?htmlfile=Fluke-track.htm

I found it well worth reading and may inspire you to try a mini development program, if you do I am sure everyone here would love to hear your results. One of the challenges of directly transferring the test process over is the hugely different profile between a car tyre and a bike tyre making the measurement across the tread much less useful but what it does tell you is if the tyre is moving outside of its recommended or even safe range. Plus there are heaps of useful things you can test on the bike with an IR thermometer.
Regards,
K-Bike

    

otto59

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can you get nitogen for tires in israel? filled up my k100 rt to specs, no worry about temperature variances. good luck.

    

roys

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Hi,

After reading some more and getting some private replies as well I decided to go by specs for my pirelli tires.

If and when I take summer rides in realy hot areas around dead sea and other deser areas I will, after 30-60 minutes stop, measure tire pressure and decide on the spot what to do. But it is most likely I will go there only in winter when temp is down to 25C. In summer it is madness to suit up and drive there.

Other then that it is mostly mediterenean climat, can be hot but issue should not be a real problem.

Thank you,
Roy

    

K-BIKE

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Hi Roy,
A couple of points if you plan to change pressures away from what is recommended by the mfr then bear in mind that lower pressures cause the tires to heat more and heat is the enemy of tire life. I have seen under pressure tires so hot you can carve the rubber out with a finger nail. Not a good thing for a road tire. With regard to inflating your tire with nitrogen that is a marketing trick to deflate your wallet. Air is Nitrogen (N2): 78.09%, Oxygen (O2): 20.95%, Argon (Ar): 0.93%, Carbon dioxide (CO2): 0.038%, Others (less than 0.002% each): Neon (Ne), Helium (He), Krypton (Kr), Hydrogen (H2), Xenon (Xe). Nitrogen fill was addressed in Consumer reports the differences seem minimal over a year http://blogs.consumerreports.org/cars/2007/10/tires-nitrogen-.html and all gases expand when heated

    

roys

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Hi,

I never heard of nitrogen in tires before this thread; seems too exotic for my present riding skills and perhaps this bike.

What you say makes a lot of sense; marketing does seem to rule the day over technologists in this and many areas.

I do a lot of reading and intend to gain mastery over this machine, performing more complex procedures over time.

However I am very aware of the diminishing returns from investing in exotics, most likely the best thing I can do to improve the performance of my bike is to lose 15kgs Smile

If I ever do drive down in the desert in summer, I will simply make sure pressure does not rise to much.

Roy

    

Morley

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The practice of using nitrogen in tires has been used for decades in aircraft tires. The main difference between using nitrogen over just air is temp. related. But not because of expanding gasses, it is because of moisture. As the air in a tire cools the moisture condenses and the pressure drop will be more drastic than had it just been nitrogen. Nitrogen won't hold moisture.

    

roys

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hi,

Interesting point; this is good and important information. Further making a differentiation based on ambient humidity, in the desert this is VERY low. Less water in air --> less important is nitrogen , however these behaviors may not be linear at all.

Regardless this is academic as I doubt my riding is in this zone - but if and when I go down to the desert, in the summer, on a bike, I will certainly monitor tire pressure very carefully

Thank you,
Roy

    

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