Metzler Z6 wear problem?

[2dollarbill]

I have 3500 miles on a pair of Z6's. The wear pattern is really strange - at least to me. The sides of the front and rear are cupping severly, the rear more so. And they also show what I think is described as flat-centering.
I have a call into Metzler, but thier Tech Rep is at Sturgis. Has not retuned my call of a week ago.

So I am asking the next best experts I know, the St-Owners. Is this a normal wear pattern? Is it normal at 3500 miles? See thumbnails. I wet tires so imperfections show up better in the pics.

I never let the tires fall below 40 PSI. I normally run 42/42 psi front and rear. The wheels are not balanced - but the cupping at every tread does not seem to be balanced related. I think the cupping would be every other tread if the wheels were out of balance.

Should I be concerned about a decreased contact patch in turns?

Any help or opinions would be appreciated. A few tire dealers and local motorcycle parts store are also bewildereed as to the root cause of this wear pattern.

 

[Jamie Z]

Hope it's not a problem. Mine are the same way. I have a flat spot in the center, and angle to that flat spot on each side is another flat spot.

I've kinda thought that the angle is likely my "usual" cornering angle. I don't notice it while I ride... either that or I've grown accustomed to it.

Jamie

 

[CCC]

That looks alot like my stock dunlops. The flat centering is dew to the harder rubber compound in the center of the tires. The sides wear faster so you get that ridge where the two different compounds meet. And the cupping in the first pic is caused by the force of acceleration and the rubber getting pushed into the groove (water sipe) so it dosn't wear as fast as the rubber that has no groove to get pushed into.

 

[2dollarbill]

That looks alot like my stock dunlops. The flat centering is dew to the harder rubber compound in the center of the tires. The sides wear faster so you get that ridge where the two different compounds meet. And the cupping in the first pic is caused by the force of acceleration and the rubber getting pushed into the groove (water sipe) so it dosn't wear as fast as the rubber that has no groove to get pushed into.

Gee CCC, that is a new explanation of the cupping I have never heard before. I guess it theoretically makes sense. The tires I wore out on my Honda Shadow wore out evenly all over. Of course they were stock OEM tires designed for a cruiser. Maybe that made the difference in wear pattern.

Jamie, I do not feel any problems with handling or any wobble due to balancing. I have felt no vibration that I can attribute to the tires all the way up to 121 mph. I still do not feel confident in tires that wear this way or convinced the wear is "normal".

 

[dannyk]

The wear is normal I have seen it on GL1800 rear tires also. If you look at the front tire on your bike you may notice the same type of wear pattern starting only not as noticeable. If you run your hand one way over the tire it feels smooth, run it the other way and it will feel like the edge of a saw blade. Eventually when leaned over you will hear a howl from the rear tire that will disappear when you stand the bike up again, all normal in tire wear patterns.

 

[huxtablejones]

when I bought my FJR it had z6's on it. I hated them. That funky wear pattern made transitioning through apex a friggin nightmare.

the following is theory, not based on any actual test

As you roll over onto the corner of that flat spot the tire seemed to lose contact area, got squirrelly - which I can deal with on the rear, but on wet pavement a few times I SWEAR I felt the front wiggle around on me. Not a good feeling.

Once you leaned in far enough to get past the corner of that flat spot, it was like the tire was constantly pushing to get back on it, trying to stand the bike up. I had to keep positive down pressure on the inside bar to keep the bike on its angle. Something I'm not used to and couldn't get used to.

I could deal with everything, though, except the loss of contact as you leaned past that hard corner in the tire. I ended up getting Shinko's(sp?) to replace the Z6's and they are OK...not great, but OK. I can feel the sidewalls flex under heavy cornering loads. Up to 7/10ths ride they are real decent.

My next tire will be the Pilots, I think. Maybe new Z6's are great, I dunno. I have run ME880's(awesome) and tourances(awesomer) on various bikes and been very happy. But man, once they got that corner on 'em they(Z6) stank like a closet full of hot grouper.

YMMV. Literally.

 

[dduelin]

I've got about 3,000 miles on a set of Z-6's and the wear seems normal to me. There is a slight amount of cupping but about what I saw on the Pilot Roads that I rode before these and less than the Bridgestone 020's that came on it. When it is time to replace the Z-6's I could go back to the PR's or another set of these as both are great cornering tires for me.

 

[NormanPCN]

That wear on the side is normal. It is telling you our tire is gripping when you are accelerating off corners. If you just roll corners you will "cup" (scallop is a more correct term) less or none. Accel hard and you get more. The softer the tire the more the effect. The tread pattern also affects this a little.

Once on a new set of Avons I did a local tight road and saw some immediate scalloping since I was using a bit of throttle off. The next day I was on a road where I mostly ride the pace and thus rolling the corners and the scallop I saw was scrubbed off/smooth. FWIW I the Avons scalloped more than the Z6 and way more than the 880 rear for me. Duh the 880 is a harder rubber tire than the other two. 3 sets of Avons and only one Z6 rear so not an ideal comparison.

 

[RTETR]

I've about 8000kms my Z6's and they look much the same as yours do but I really don't see much, if any, cupping on the front just slightly more wear in the center. I run both at 42psi and they are far better tire than I found the BT020's to be for performance, ride comfort and feedback.

Most all of my saddle time is loaded with one up and I did have cupping on the front BT020 no matter what I set the psi at and I ran the rear for 24000kms before replacing both. I am very satisfied with the Z6's.

A couple buddies on RT's also run the Z6's and have seen much the same wear patterns. One RT just replaced his Z6 rear tire after running it hard for about 22000kms. He actually had threads/belt showing when we got home from a trip a couple weeks ago!

Anyhow, what you have seems to be the "norm" for the Z6's.

 

[2dollarbill]

Thank you for the feedback, gentlemen. I guess what I thought was abnormal wear is normal wear for the Z6. That is comforting to know that it is not just my tires showing that kind of wear. Now my decision is how soon do I trade these out for a new set of skins? And what kind of skins the next time around?

 

[saaz]

Looks like my Z6s as they approached 10,000kms. Seems to be normal wear.

 

[NormanPCN]

Thank you for the feedback, gentlemen. I guess what I thought was abnormal wear is normal wear for the Z6. That is comforting to know that it is not just my tires showing that kind of wear. Now my decision is how soon do I trade these out for a new set of skins? And what kind of skins the next time around?

Avons wear better than the Z6's and stick just as well or better. IMO. A little softer feeling tire up from verses the Z6. As so as my Z6/880 CanSTOC combo wears out I will be trying the Pilot Road just to see what they are like. You never know until you try. Then again the new Avons might be out by then. Oops, I should not have said that.

If you like the Z6 front and want better wear in the rear you might want to try the Z6/880 combo. The 880 is surprisingly good for a pure "touring" tire.

 

[JReviere]

If you wish to understand the wear dynamics of the tread blocks under power for the rear and under braking for the front, take a new pencil, put the eraser on a piece of paper with the pencil held verticle. Now with mild pressure down on the eraser, slide the pencil to one side... Notice how the leading edge of the eraser takes most of the force and the trailing edge just goes along for a ride as the eraser actually bends toward the trailing edge.

On your front tires when you brake, the tread blocks do the same sort of thing... those toward the front take the bulk of the force and the blocks actually "bend" ever so slightly to the rear causing a scalloping wear pattern in which the leading edge of the blocks wear faster than the trailing edges to.

Just the opposite is the case on the rear where the tire is under pressure far more due to application of power than it is to braking force. Different tread patterns, of course, wear differently as do different tread rubber compounds.

Many mc tires are made with a slightly harder compound in the center of the tread to wear longer since that's where the vast majority of wear is concentrated due to long periods of time rolling upright. When a bike is heeled over in a turn, the tread rubber on the shoulders takes on added importance in which GRIP is essential, thus a softer compound is used there. The softer the compound the more block squirm with scallop type wear is a natural consequence of the need for greater "GRIP" on the shoulders of the tire.

I have Z-6's with about 8Kmi on them... they look almost IDENTICAL to the tires in the fotographs.

JR
394
Lake Livingston, TX

 

[JReviere]

If you wish to understand the wear dynamics of the tread blocks under power for the rear and under braking for the front, take a new pencil, put the eraser on a piece of paper with the pencil held verticle. Now with mild pressure down on the eraser, slide the pencil to one side... Notice how the leading edge of the eraser takes most of the force and the trailing edge just goes along for a ride as the eraser actually bends toward the trailing edge.

On your front tires when you brake, the tread blocks do the same sort of thing... those toward the front take the bulk of the force and the blocks actually "bend" ever so slightly to the rear causing a scalloping wear pattern in which the leading edge of the blocks wear faster than the trailing edges to.

Just the opposite is the case on the rear where the tire is under pressure far more due to application of power than it is to braking force. Different tread patterns, of course, wear differently as do different tread rubber compounds.

Many mc tires are made with a slightly harder compound in the center of the tread to wear longer since that's where the vast majority of wear is concentrated due to long periods of time rolling upright. When a bike is heeled over in a turn, the tread rubber on the shoulders takes on added importance in which GRIP is essential, thus a softer compound is used there. The softer the compound the more block squirm with scallop type wear is a natural consequence of the need for greater "GRIP" on the shoulders of the tire.

I have Z-6's with about 8Kmi on them... they look almost IDENTICAL to the tires in the fotographs.

JR
394
Lake Livingston, TX

 

[2dollarbill]

Thanks again, gentlemen, for your continued feedback. I do appreciatte how open and helpful the folks on this forum tend to be.
All the reasons suggested for the tire wear I am experincing sounds pretty close to what is happening. I am still dissapointed the wear is so severe a just 3500 miles. Oh well - the price we have to pay for having more fun than we should be allowed to have.