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Discussion Starter #1
So when I got back from my last track session I noticed a very strange tire wear on the rear. Tires are Dunlop GPA Pro medium compound. I sent these images to the Dunlop distributer where I bought them (this distributer supplies all the spec tires for MotoAmerica races). After a couple days he called me back and said that neither he nor Dunlop reps up the ranks have ever seen tire wear like this. They are speculating from the pics that the HP to the rear wheel was deforming or changing the contact patch to the pavement and resulted in parts of the tire not getting wear.. or at least that’s what little I got out of the explanation on the phone. They’ve asked me to ship the tire to Dunlop in Buffalo so they can cut into it for further examination. They are sending me a new tire + shipping label. I’m thinking this is probably a unique situation with this tire, cause I doubt anyone has put GPA Pros onto an H2R.

BTW the tires were new when I went to the track and I rode all sessions on TC1



 

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Same didn't happen on both side? I would say it's something to do with the tc. If it happens on the next set it may be worth doing a couple of laps at 90% but with tc off. I got some odd patterns on my stock tyres after some moderate road riding but nothing that drastic, was obviously tc interference, it was on tc2
 

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Tire deformed in the mold ? Like it was raised and then shallow ? Like humps up and down, so the humps were taking all the concrete and the valleys didnt touch ?


NOLA
 

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Discussion Starter #5
Tire deformed in the mold ? Like it was raised and then shallow ? Like humps up and down, so the humps were taking all the concrete and the valleys didnt touch ? NOLA
no it wasn't a mold issue, the tire looked normal fresh, and I doubt it was a tire issue, more likely it was an issue with the amount of power delivered to the rear wheel deforming the contact patch to the surface. But like Vmax brought up it is strange that it wasn't on both sides.
 

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Strange it wasn't on both sides but based on the universal pattern around each sipe almost looks like when leaned on the edge of the tire the rubber was folding in at each sipe where there is essentially a weaker point/cut/less rubber, so not contacting the pavement w/ as much pressure.
 

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Wow.. That looks really bad. I was hoping to throw on a set of Dunlop's this season but I might just stick with the OEM's. Did it cause any issues while you were out on the track?
 

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Doubt it's a hp issue seen lots tyres from bikes with LOTS more horsepower than a H2 with normal track wear. I would guess it to be suspension set up issue, faulty valving or electronic failure within the system.
I ran GPAs for years and were a reliable tyre, but another possibility is carcass is faulty as been said already...
Tyre manufacturers are always in denial about their product (if defective or fails) for obvious reasons (assuming the tyre is defective) and have seen similar responses in the past in which they supply another tyre to keep you "happy". I wouldn't trust them one bit. Had my own problems with manufacturers tyres and other bike suppliers and are always reluctant to be truthful or take accountability.
If nothing is resolved by the tyre experts I would be inclined to put another one on the bike and turn off t/c to eliminate that possibility, then start looking elsewhere... just a thought
Be interesting to see what it is
 

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if you lift the rear off the ground and have someone tray wriggle your tyre \ rim side to side does it move? it could be a defective rear bearing
 

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That type of wear is usually associated with suspension set up and/or tyre pressures, however, were you feeling the TC biting more on a particular corner

With regard to it being one side only, doesn't matter, when you ride on a track, the corners/speed/lean angle/contact surface are inevitably different on left and right handers

Rob
 

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very strange and impressive Dunlop are sending u new tyres and looking into this.

how did it feel on track and how much time did you spend on track to get them to this state
 

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So when I got back from my last track session I noticed a very strange tire wear on the rear. Tires are Dunlop GPA Pro medium compound. I sent these images to the Dunlop distributer where I bought them (this distributer supplies all the spec tires for MotoAmerica races). After a couple days he called me back and said that neither he nor Dunlop reps up the ranks have ever seen tire wear like this. They are speculating from the pics that the HP to the rear wheel was deforming or changing the contact patch to the pavement and resulted in parts of the tire not getting wear.. or at least that’s what little I got out of the explanation on the phone. They’ve asked me to ship the tire to Dunlop in Buffalo so they can cut into it for further examination. They are sending me a new tire + shipping label. I’m thinking this is probably a unique situation with this tire, cause I doubt anyone has put GPA Pros onto an H2R.

BTW the tires were new when I went to the track and I rode all sessions on TC1





Just wondering, do you use the rear brake at all while leaned over to tighten your corner arc?


The uneven wear is not deep enough to be a construction issue and there is no missing rubber. On the other hand it does seem inconclusive.
 

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What about some flex in your BST wheel rim? The right side has more support from the spokes but the left side has less. Personally I don't like the fact that Dunlop chose to put tread blocks right in the place where you need the most traction? Maybe they want the rubber to move around a lot at that lean angle to keep heat in the tire?
 

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Discussion Starter #16
Did it cause any issues while you were out on the track?
No, none, didn't even notice it.

how did it feel on track and how much time did you spend on track to get them to this state
felt fine, no issues. My best guess is I rode about 30 laps with Benny Solis on Sat and about 50 laps on my own on Sunday pushing a little harder.

do you use the rear brake at all while leaned over to tighten your corner arc
no not on the track I don't. on the street sometimes

too much pressure?
don't think so. I was running 35f 21r hot off the warmers and I was checking through the day. It was about 60f that day.

What about some flex in your BST wheel rim? The right side has more support from the spokes but the left side has less.
Yes I agree this is the most likely cause, flex in the rim or swingarm. It has been suggested that I put the stock rims back on and recreate the same conditions. If this continues I may just do that.
 

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Discussion Starter #18
It's not the rim. Carbon exhibits little to no flex at all. It will simply fail.
my guy (builder) agrees with you, said would simply crack.
He also said if it was a suspension issue that it would most likely be too much rebound, but if it was a suspension issue he would expect to see it on both sides. He thinks it's a tire issue.
 

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My H2 was getting shimmy at high speeds at the track in triple digits, one cause that was found was the rear wheel left nut was not as tight as it should have been. It has since been fixed but not sure if the shimmy (vibration would be a better word) has gone away. Won't know for sure until I can test it under the same conditions.


Rhody...
 

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Discussion Starter #20
My H2 was getting shimmy at high speeds at the track in triple digits, one cause that was found was the rear wheel left nut was not as tight as it should have been. .
I haven't had any handling problems and I've been taking high-speed turns at 160mph in the canyons and straight runs up to 190, so I don't think I have your problem, but I am interested in what nut you are talking about, is it that star-shaped nut that has about 12 points on it?
 
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