What is cupping?

EXPATRIATED · Mar 8, 2011

I've seen the term "cupping" in almost every thread on tires. I'm sure this is a dumb question to most of you but what exactly is "cupping"? From the context it is used in, I can gather that it has to do with the wear on a tire but I'm not sure exactly what people are referring to. What does cupping look like?

In a search of the forum for the answer, I even turned up a thread that said that the tire was cupping on only one side??? but no definition.

So, any help you can give to a mechanically challenged rider would be appreciated. Thanks!

MotorradMike · Mar 8, 2011

For me it has occurred only on the front, both sides but more on one,
Looks like scalloping.
Kindof like a tiny spoonfull got scooped out from each tread block.
Happens more on tires with blocky tread patterns. My Pilot Road lls seem immune.

Easier to see if you play a flashlight along the tire.
Noticeable if you are turning as a hum(depending on speed).

That should be enough!

akbeemer · Mar 8, 2011

Cupping..... something done in the back seat of a 55 Buick Special.

chiba · Mar 8, 2011

http://www.expresstire.com/tire_wear.shtml

Lots of good info on that page.

--chiba

EXPATRIATED · Mar 8, 2011

Great info, guys, thanks! Now, I'm speaking BMWMOA a little more fluently.

Except for you, AKBeemer, that was useless

Besides, it was more like a 1982 Eagle AMC for me :brow

lmo1131 · Mar 8, 2011

And here I thought you guys were talking about the Chinese Acupuncture practice called "cupping" ...

They hold a match under the inverted "cup" to heatthe air inside, then when the cup is placed on the skin the air cools and contracts causing the skin to be drawn into the cup (pulling extra oxygen/blood and good juju along into the affected area).

EXPATRIATED · Mar 8, 2011

ewww...can't say I saw that coming :sick

rockbottom · Mar 8, 2011

MotorradMike said:
For me it has occurred only on the front, both sides but more on one,
Looks like scalloping.
Kindof like a tiny spoonfull got scooped out from each tread block.
Happens more on tires with blocky tread patterns. My Pilot Road lls seem immune.

Easier to see if you play a flashlight along the tire.
Noticeable if you are turning as a hum(depending on speed).

That should be enough!

My PR IIs on an F800ST cupped very badly. There was a protruding ridge.

rx35285 · Mar 8, 2011

rockbottom said:
My PR IIs on an F800ST cupped very badly. There was a protruding ridge.

So did mine. Any ideas what to do about it?

35634 · Mar 8, 2011

My ME33's did it. I heard that the leading edge of the tread block us relatively stable, but the trailing edge will squirm, causing more wear on the back edge of the block. Eventually your tread blocks are a series of wedges. I have no idea if this is factual, but it sounds good.

marchyman · Mar 8, 2011

35634 said:
I heard that the leading edge of the tread block us relatively stable, but the trailing edge will squirm, causing more wear on the back edge of the block. Eventually your tread blocks are a series of wedges. I have no idea if this is factual, but it sounds good.

Looks good, too... Notice the wedge shape to the knobs at the bottom of this pic.

They don't look that way on a new tire. :deal

rockbottom · Mar 9, 2011

rx35285 said:
So did mine. Any ideas what to do about it?

I know this is controversial but when I put Dyna Beads in my next set (same bike, same roads, same rider) it made a significant difference. I now have Z3s and they haven't cupped.

Darryl Cainey · Mar 9, 2011

I couldn't resist!

vtbob · Mar 9, 2011

As has been said already, cuping happens when the tire deforms when in contact with the road and wears in a non uniform way. When there is significan cuping on the front it can be felt in the handle bars.

Cuping is accelerated with low tire pressures. On the rear, twisting the trottle hard speeds it up too. As does hard braking on the front.

Tire design has a real impact. In my experiance the stiffer the radial belt the less cupping. or as a coralary soft belted tire are more prone.

Almost all...no all my front tires show some signs of cupping by the time there are worn out. On an earlier bike, M33 cupped so bad I had to change them before they were worn out.

pffog · Mar 9, 2011

Suspension plays a big part in cupping too, a properly set up, high quality suspension will greatly reduce cupping.

Lets face it if you are on original suspension at 20K miles, you are on a worn out suspension. Yes high quality aftermarket is big $$$, but pays for itself in many ways (better tire wear, fewer chiropractor visits, fewer bent rims, better handling, happier passenger etc) and when you sell your steed, reinstall the OEM and sell the aftermarket for 2/3 of what you paid!

cycleman2 · Mar 9, 2011

MotorradMike said:
For me it has occurred only on the front, both sides but more on one,
Looks like scalloping.
Kindof like a tiny spoonfull got scooped out from each tread block.
Happens more on tires with blocky tread patterns. My Pilot Road lls seem immune.

Easier to see if you play a flashlight along the tire.
Noticeable if you are turning as a hum(depending on speed).

That should be enough!

My PR II's cupped on both sides of the front tire ( left side was worse than the right ) and the rear cupped as well but not as bad as the front. The tires had about 7 K miles on them from one trip last fall. The bike was loaded up ( no passenger ) , many high speed sharp twisties, heavy braking, fairly high speeds at times, etc. Created a vibration at very low speeds when turning left. That started happening when the tires had about 2 K miles on them.

The ME 880 that was on the front previously showed no cupping.

Cupping of tires on these bikes seems to be a common trait. It may have something to do with the front & rear tire not exactly tracking each other.

ANDYVH · Mar 9, 2011

On the issue of suspension relative to tire cupping, I can certainly confirm that worn out dampening in shocks increases tire cupping. The front tire on my 94 RS used to cup significantly, no matter the brand.

Then I finally replaced my clapped out crappy stock shocks for Wilbers and the cupping is minimal at most, now after three sets of tires. So in my book worn out shocks contribute to significant cupping as much as does low tire pressure.

When the dampening action of shocks are gone, the suspension "flutters" up and down at a fast enough rate that we can barely feel it. But, that constant vertical flutter greatly wears the trailing edge of any tread block, leading to accelerated cupping.

tourunigo · Mar 9, 2011

AKBeemer said:
Cupping..... something done in the back seat of a 55 Buick Special.

.... how about a 1960 three cylinder Saab with no shocks in the back :dance

That Buick would have been nice though.... straight eight takes on a whole new meaning eh?

Kevin, are you at Bloomsburg this year. Ok, back to topic. - Bob

gertiektn · Mar 11, 2011

I'm with u AKBEEMER... I like 55 Buicks.

As for the rest of you good info here...

But light reading makes it all the more interesting.

My R1100S had 10k on the tires when I bought it and the cupping was very evident.. I surmised that the PO was on the front all the time.
I have since replaced the tire and now with 3k on it.. no noticable cupping..

I particulary liked the post with the bottles on the guys back..

I learned that there are many definitions of cupping..

Thanks all. :groovy

Jim, Ketchikan.. we both get the Perm Fund Dividend.

Roy.Jackson55@aol.com · Mar 11, 2011

Darryl said:
I couldn't resist!

Funniest thing I have seen posted in a while. Very original, though I have been told that I have letÔÇÖs say an unusual sense of humor

What is cupping?

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