Tire PSI question - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 20 Old 08-15-2014, 11:16 AM Thread Starter
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Tire PSI question

Since I got my new tires I want to stay on top of the PSI more. 8/8/214 they were at F 34 R 36. 8/15/2014 they were at F 29 R 32. Does that seem normal for tubed tires after a week with a 500+ KM


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post #2 of 20 Old 08-15-2014, 11:33 AM
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Yes.

Tires, tubes, and valve cores are semi-permeable to gasses. Gas molecules can leak out.

You might try removing the valve cores and moistening the small seal and then re-installing it, as your valve stem may be a bit leaky.

This is why using nitrogen in car tires is somewhat popular, though at a premium price. The nitrogen molecule is larger than an oxygen molecule and therefore the tire/tube/valve core is less permeable to it.

"I use a custom blend of gasses that are 78% nitrogen, 21% oxygen with some trace impurities at 1%", Tom said airily.

Tom

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post #3 of 20 Old 08-17-2014, 04:34 PM
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Mine lose a fair mount of air if they sit for the week. I check my pressures every day before my first ride and wouldn't even think of wheeling it out after a week and riding it without checking them.

Interesting note about the molecule size between nitrogen and regular air, Tom. I didn't know that. I always just thought nitrogen was preferable due to less water/moisture and, in the case of aviation, keeping a more stable pressure with altitude differences.

We always used nitrogen in Army helicopter tires, but strangely enough never really regularly checked tire pressures with a guage and just noticed when they "looked a little flat." I think it was called for during a weekly inspection, but we never did it.

Even though I check my KLR tires religiously, I'm really bad about not checking our car tires. I can honestly say I'll go 4-5 months without paying any attention to them at all and that's probably not good.



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post #4 of 20 Old 08-17-2014, 04:54 PM
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Quote:
... I always just thought nitrogen was preferable due to less water/moisture and, in the case of aviation, keeping a more stable pressure with altitude .. .
planalp-

I think you are more correct than I am.

Tom

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“On the way downtown I stopped at a bar and had a couple of double Scotches. They didn't do me any good. All they did was make me think of Silver-Wig, and I never saw her again.” -Philip Marlowe

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post #5 of 20 Old 08-17-2014, 05:34 PM
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Not disputing your theory in any way, Tom. I really know nothing about it. Did find this, though:

http://www.google.com/url?sa=t&rct=j...73231344,d.aWw



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post #6 of 20 Old 08-17-2014, 07:38 PM
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Noted, but you're still more correct than I.

Nitrogen does permeate more slowly than oxygen, but what is probably a greater advantage is that nitrogen is a dry gas and there is less moisture in the tire. That translates into greater pressure stability over a range of temperatures, as inflating tires with common 'ya pays yer quarter' air lines can introduce a lot of water into the tire.

Do you think it was Archie Graham?

I stand by my custom gas mix as being the best for everyday use (it's pretty dry stuff at my house).

Tom

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“On the way downtown I stopped at a bar and had a couple of double Scotches. They didn't do me any good. All they did was make me think of Silver-Wig, and I never saw her again.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

Sting like a butterfly.
Noli Timere Messorem

Last edited by Tom Schmitz; 08-18-2014 at 10:36 AM. Reason: forgot 'dry'
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post #7 of 20 Old 08-18-2014, 10:11 AM
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Let me confess that I use nitrogen in my KLR tires (this usually gets the nitrogen haters going ).

I commute daily, 70 mile round trip, year around. On the weekends I'm a recreational rider. So, I like to keep my maintenance chores as simple and few as possible.

Over the years I've found that with nitrogen, my tires loose about 1 to 1 1/2 psi in two weeks time. Using air, they lose about two lbs per week - quite a bit more.

The nitrogen doesn't cost all that much. I get it at welding supply stores. A tank seems to last several years.

Ron

Opinions are my own. Everything I describe is very likely wrong. Use at your own risk.
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post #8 of 20 Old 08-18-2014, 10:12 AM Thread Starter
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I wonder if Helium in the front tire would help with the wheelies.


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post #9 of 20 Old 08-18-2014, 10:25 AM
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No, that will cause a bad tweetie in the exhaust.

Try sulfur hexaflouride for a deep, resonant exhaust note.


Tom

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“On the way downtown I stopped at a bar and had a couple of double Scotches. They didn't do me any good. All they did was make me think of Silver-Wig, and I never saw her again.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

Sting like a butterfly.
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post #10 of 20 Old 08-18-2014, 04:41 PM
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I don't know. Call me weird, but there's something comforting about that nasty water/rubber stench that's expelled from a tire that's been on for awhile. It's as much a constant in life as death and taxes, from my first bicycle to the current KLR. I don't recall nitrogen-filled tires gracing me with such a precious gift.

Other than that, I've got no issues with using nitrogen. Indeed, a full 3,000 psi tank of nitrogen would last a long time.



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