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cupping on my rear tire


Hoblick
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i have had these dunlop road smarts on for about 5500 - 6000 miles now.

the rear tire has some cupping/scalloping going on.

whats the deal?

i this normal? havent checked the pressure lately, but it was spot on last time i checked.

and the dual compound is nice, but it almost makes the tire square off quicker. cause i do hit alot of twisties, and the the center (hard compound) wears alot less its peaked and squared..

ill have to upload some pics tomorrow.

i like these tires, they grip very well for a dual compound tire, but im not liking the wear patterns they are forming.

i guess ill be trying out the Michelin Pilot Road 2 tires next go round

id like to just throw some pilot power 2ct but i know i wont get any mileage at all out of them.

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heres where i found that info

http://www.rattlebars.com/valkfaq/tirewear/

CUPPING:

Cupping, which is more accurately described as scalloping (see pictures, but we will use the more common term "cupping" here), is a natural wear pattern on motorcycle tires and it will always follow the tread pattern. It is not a sign that you have bad suspension parts. It merely shows that your tire is indeed gripping the road when you make turns (thank you for that Mr. Tire!). This cupping develops within the side wear bands of a leaned motorcycle. The extreme forces that come in to play when the bike is leaned in a turn are what produce the effect and when the wear becomes sufficient, one will experience vibration and noise when one banks into a turn. Upon examination of the pictures at left of our sample rear Avon, our dusted front VTX Dunlop D256, and the picture of our chalked Dunlop D206 one can see how the cupping follows the tread pattern. The leading edge of the tread does not flex much as it grips the road and the rubber is scuffed off the tire in that area causing a depression. As the tire rotates, the pressure moves to the trailing edge of the tread pattern where the tread flexes more causing less scuffing so less material is ground off the tire. The more complex the tread pattern, the more complex the cupping pattern will be. The softer the compound of the tire, the sooner this cupping will develop. Radial tires are more prone to cupping than are bias ply because the compound of radials is softer. As one can see, the simple tread pattern of the Avon pictured produces a simpler scallop pattern while the more complex VTX D256 Dunlop is somewhat involved, though still easily seen in our photo. Cupping on the Valkyrie Dunlop D206 is very hard to photograph because of the complex tread pattern. Low tire pressure will exacerbate this wear pattern and you will lose many serviceable miles by running low. Improper balance has nothing to do with cupping on a motorcycle tire. Improper balance will merely cause your bike to vibrate within certain specific speed ranges.

The following textual illustration comes from Martin who contributed to this article by E-mail on June 26, 2006:

I was just reading your bit on "cupping" and thought I'd share with you how I describe what's going on. I usually tell people that what's happening is that the individual "blocks" or "islands" of tread are squirming and deforming due to the forces applied to them during cornering and braking. When this deforming takes place, the wear is naturally not evenly distributed across the surface of the tread. (I define a tread block as an area of the tire surface surrounded by a groove.) I next tell people they can demonstrate to themselves what's happening by taking a new pencil with an unused eraser on the end and while holding the pencil perfectly vertical, push down and drag the eraser on a rough surface in one direction. Then I tell them to look at the eraser and note that all the wear is on the leading edge and not evenly distributed across the end surface of the eraser. It seems to make the concept easier for many to understand. Cheers!

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I accelerate hard out of the corners too, but I've never had much cupping on the rear. I always seem to always have it on the front thire.

Do you think the mounted luggage could have thrown off the pressure and/or wear characteristics of your bike?

I have also noticed the dual compound tires I have used always squared off which can kills lean-in confidence.

Maybe I'll put a single on the front and dual on the rear. :dunno:

Edited by RC51 John
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checked air pressure

35 in rear

25 in front (front has no cupping)

i do think with the added luggage, and 2 up riding i do may be some of the culprit.

i increased pressure to 38 in the rear and 38 in the front..

im not sure what pressure to run these at since ive heard different answers for the dual compound tires

here are pics

SL371634.jpg

SL371635.jpg

SL371636.jpg

SL371637.jpg

SL371638.jpg

SL371639.jpg

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also another question.. after a run through a real good seat of twisties, i get that rubber curl..

kinda like when the tire has heat up and starts to kind of peel or curl off from the road..

normal, or should these tires do that through a 7 mile stretch of twisties

like i said before im new to really riding hard through the twisties this year lol

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the tire looks good man, nothing more than what you would expect a normal tire to do. you may wanna consider increasing your tire pressure when ever you have a passenger tho. i run 34/36 on my corsa 3's for street riding when its just me but i crank up the rear to 40 if ive got a backpack

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