Unusual Front Tire Wear

paulcb

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I'm experiencing very unusual tire wear on the front of my '01 ST1100 with 40k on it. The tire is a Metzler Roadtec Z6 and has at least 8k on it. It was on when I purchased the bike and looked good then. I've put about 2k on it since purchase, 95% on slab. Here are some pics and a video...
Tire 1.jpg IMG_0388.JPG [video=youtube_share;16AQ7QYE-Pg]http://youtu.be/16AQ7QYE-Pg[/video]

You can see the asymmetrical wear in the first pic and the demarcation line on the right of the 2nd pic where that wear starts. If you look real close in the video, you can see the flat spots.

When running down the road on new flat concrete, I can really feel the front end rebounding up/down at different speeds. I think when the frequency of the flat spots gets near the resonant frequency of the loaded suspension is when I feel it the most. This has all happened pretty much in the last 1000 miles. I think most of it has happened in the past 500. I looked at it a couple hundred miles ago and it was cupped but I don't think it had the non-symmetrical wear like I'm seeing now. As far as I know the suspension is stock and I didn't think it had any problems... no leaks and no visual issues. And to add, ~42psi front an rear. (thanks for the reminder Mcreviver)

So, any guesses on what's going on?

Thanks for all the help!

Paul
 
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Uneven side to side wear is from crowned roads. Bouncing is an indication you may need to recheck the balance of the tire/wheel assembly. Wheel bearings okay? I run Z-6 on the front of my 2000 and I like the handling. When the tire is near the end of it's useful life it will howl when leaned into a turn. It's bothersome but not problematic. Are you running 40 to 42 PSI ? From the photos it looks like that tire wouldn't pass state inspection again. I would replace one in that state of wear.
 
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paulcb

paulcb

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Thanks Mc. FWIW, I would say that about 25% of my riding is on a crowned road. Yes, I think the wheel bearings are OK... the wheel spins smoothly and has no play.
 
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Looks like it's time to tune-up the forks... possible new springs and fluid and maybe some new bushings. I was getting tire wear similar to yours and rebuild the front end and all the unusual wear went away... front tire is smooth, no feathering, no cupping, no asymmetrical wear. After rebuilding the forks, get a new tire as that one seems to be too far gone to ride even with a new front end build.
 
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paulcb

paulcb

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I'm hoping it's not a fork issue... the bike only has 40k on it, but it is 12 years old. I've got another tire sitting on the garage shelf but don't want to mount it until I figure this out.

Another data point... I upped my tire pressures from 36-38 to 40-42 psi a few hundred miles ago, about the time I really started to notice this.
 

Tom Mac 04a

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With the low pressure you were running, I'd prob bet it was more that than the 12k forks....

I find I usu run both front /rear at 42psi, as per manf recommended.
 
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Paulcb,

I have run several z-4's and z-6's on my 2001 ST1100 and with each one got the wear pattern you picture. Rather than continue to chase the Metzler price increases I switched to Bridgestone 20's and got a better ride and increased mileage and even wear. The 20 apparently hasn't heard of the road crown theory.

Jim
 
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paulcb

paulcb

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Paulcb,

I have run several z-4's and z-6's on my 2001 ST1100 and with each one got the wear pattern you picture. Rather than continue to chase the Metzler price increases I switched to Bridgestone 20's and got a better ride and increased mileage and even wear. The 20 apparently hasn't heard of the road crown theory.

Jim
Thanks Jim. Interesting info. I believe the crown theory, I'm just a little hesitant to assign it as root cause to my problem because 1) the asymmetrical wear happened very quickly and 2) I'm only on crowned roads about 25% of the time, at best.
 
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paulcb

paulcb

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Thanks for the input folks. I've decided to replace the tire with the new one I have... a BT-45 110/80. I ordered some Counteract beads today to throw in there too.
 
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paulcb

paulcb

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Installed the new BT-45. Also installed a GPS mount...ImageUploadedByTapatalk1379807883.514847.jpg
ImageUploadedByTapatalk1379807900.357422.jpg
The new unbalanced tire seems to run perfect. I'll add the beads when I get them.
 
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FWIW, I tried the beads, some of my friends with 1100's have tried them, and no good results... YMMV.
 

mi1300

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I had the same wear pattern on my rear tire, also a Z6 and it went from normal to one side worn down, just like yours did. Mine happened over approx 4-500km. Once I noticed it, I watched in closely and didn't trust it anymore so changed both front and rear. My front was evenly worn. It's almost like it reaches a point of compound change and goes down very quickly.

Mike
 
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