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post #1 of 29 (permalink) Old 07-23-2008, 08:39 AM Thread Starter
 
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500R Rear Tire

Can somebody please look at the tire I'm running and give me some idea of how much lean angle it can take? I've leaned it pretty far but there have been a few times that were a little iffy, on whether or not it was coming back up imo. It's the best pic I could find, but look at how it's crazy narrow and also not rounded all the way like what you guys run. I'm trying to avoid trial and error on this one because it could be expensive. Is this thing made to really get used or not..?

http://i293.photobucket.com/albums/m...0603080717.jpg

Oh also, I saw something on the news about people using nitrogen instead of air to fill their tires.. It's supposed to hold air longer apparently because it doesn't contract and expand due to temperature. Any benefit/truth to this?

Last edited by RydeAddict; 07-23-2008 at 08:55 AM.
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post #2 of 29 (permalink) Old 07-23-2008, 09:17 AM
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There should be some info on the 'net about the lean angle for your tire. What is the brand/model/size?

Nitrogen inflation is popular in motorsports because it holds constant pressure (as you mentioned, doesn't expand/contract) so it is more consistent and predictable. As far as holding pressure longer, I think that would have more to do with the quality of the tire, though having a nearly constant pressure would probably extend the life of the tire (only slightly I'd imagine). I dunno. Ask the engineer. Vash?

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post #3 of 29 (permalink) Old 07-23-2008, 09:39 AM
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The whole Nitrogen thing is silly to me. Any value you might derive is probably not notable and unlikely to be worth the cost/effort required to get it put in.

As for lean angle, I used the slide method. When the bike began to slide more than it should either my speed was wrong or I was too far over. Haven't had that problem on this bike (with lean angle) but did on my old 500.

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post #4 of 29 (permalink) Old 07-23-2008, 09:54 AM
 
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The constant pressure is mostly crap!
Every gas contracts and expands with changes in temperature, and nitrogen is no exception. There is, however, one way that this can be true.

If the air in the tire is high in moisture content, than this moisture can evaporate into steam, or condense into water with changes in temperature. Under standard temperature and pressure, 18g of water makes 22.4L of steam, so its a fairly sizable difference. However, this difference starts getting negated quickly
1. Since the tires are pressurized, it takes a pretty damn high temperature to turn water into steam, much more than the standard 100C.
2. Only a very small percentage of the air is water
3. Most of the water in the air gets left in the bottom of the compressor tank
4. Many compressors have driers on them to take care of this extra moisture.

But really, its a damn sales gimmick, trying to stiff you for a few more bucks. It may make sense in professional racing, because its one less variable to worry about and whats a few more bucks when you have a couple of thouthand in even a crappy race team, but it makes no sense what so ever for the average roadracer.

As for the tire, take a picture from the back, so we can get a better idea.
Or, get a few friends, and ask them to lean the bike over (it will take at least two) while you stand behind and watch. Ask them to lean it over as far as they can, slowly, while you see which part of the tire contacts the ground. You will be able to see what the max lean angle the tires can support, it wont be as much as a sport tire, but believe me, it is waaaay out there, and I seriously doubt you are hitting it.

However, you can loose traction way before you run out of tread.



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post #5 of 29 (permalink) Old 07-23-2008, 09:57 AM
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Rule #1: Do not pay extra for nitrogen in a tire that is run on the street, even if it's a nickel a tire. If you get it for free, then it's okay, but don't expect any type of improved performance.

There are no special properties of nitrogen that make it more suitable for tires. It expands and contracts as it heats up and cools down just like any other gas. The reason nitrogen is used is that the process to separate nitrogen from the atmosphere also filters out the water vapor, plus the natural atmosphere is ~78% nitrogen, so there's plenty of it available.

In situations where there are extreme temperature and pressure fluctuations the water vapor will create havoc with the pressures. Aircraft tires that come down from a -30F atmosphere to the ground and immediately have to support 50,000 lbs at 200 mph are a good application.

Anyone who tells you that you'll get better performance from using nitrogen is either trying to sell it to you or trying to feel better about getting ripped off.

Edit: Vash, with 36 psi in the tire, water would boil at around 275F.

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post #6 of 29 (permalink) Old 07-23-2008, 11:02 AM
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There's a couple tire places around me that offer free nitrogen inflation when you buy new tires. I'm sure it's added into the cost of the tire somehow, but that's business. Personally, I've always just used a regular old air compressor, and never had any problems that couldn't be blamed on the tire itself.

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post #7 of 29 (permalink) Old 07-23-2008, 11:06 AM
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I've always just blown into the tire stems to fill mine

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post #8 of 29 (permalink) Old 07-23-2008, 11:14 AM Thread Starter
 
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Oh this is good stuff..

1.) Scratch the nitrogen idea. The guy on the program actually was an auto repair shop owner who sells it.. You guys are good.

2.) Great idea about having some friends lean the bike, I never would have thought of that. I don't know about just two though, maybe four.. It's pretty heavy. Maybe I can talk them into letting me sit on it too to get a feel for it after I check it out from behind. Maybe a long shot but we'll see...

3.) Ever since I first read about sliding the rear tire the thought of it freaks me out. I guess I need to get over that fear but bikes and sliding just doesn't sit well with me. I've skidded the front tire straight before from hard braking, but that's about it. I can do a power slide like a maniac on my quad, but I've got four tires to trust. Breaking traction on two wheels is a scarey thought.

Thanks!
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post #9 of 29 (permalink) Old 07-23-2008, 06:28 PM
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+1 on the whole nitrogen debate.

If you're starting to lean that much that you're really getting concerned about your tyres, I reckon you should just give 'em the flick and put some better rubber on there.




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post #10 of 29 (permalink) Old 07-23-2008, 08:05 PM
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I've made tires slip due to road conditions and cold temps, but the only time I've slid the rear due to (apparent) lean angles was the dunlop qualifiers I had on the Gixxer before I pledged allegiance to 2CT's. Of course the 50+ degree lean angle and super-adhesive properties of the pilots has resulted in absolutely no sliding whatsoever.

I was pretty worried about sliding myself, until I actually had it happen. It was certainly an unsettling feeling, but not horrifying. I'm not sure about everyone else, but in my case, it was more of a "wobbling" than anything. The tire would get a little out of line and then regain traction, but never be in a full-fledged "slide" as in spinning, which I've only experienced when hitting gravel or dirt on the road.

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