Tire Cupping


Technical information and Q&A applicable to all years and models of Goldwings
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tfdeputydawg
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Tire Cupping

Postby tfdeputydawg » Wed Sep 30, 2015 8:15 am



Read this in a recent post:
"Started cupping and "beads" made cupping go away :!: :?:"
Just for info for all:
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.
http://www.rattlebars.com/tirewear/index.html



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Re: Tire Cupping

Postby WingAdmin » Wed Sep 30, 2015 9:22 am

This is a very accurate article describing the cause of various types of tire wear. The one thing he states that I totally disagree with is his insistence that downshifting is not a good practice. He says you should just hold the clutch in and let the engine idle as you shift down through the gears, to save your rear tire, and reduce driveline stress.

However having your engine at idle when shifting down at speed can wear your transmission due to the difference in speeds between the input and output clusters. In addition, if you suddenly need to get out of an emergency situation, you first have to rev up the engine, match the engine speed to the rear wheel speed, then let out the clutch, and hope you matched the speed correctly. If you haven't matched it, you run the chance of locking the rear wheel.

I prefer to downshift, have my engine connected to the rear wheel so that I can simply twist my throttle to add power if I need it, and change my rear tire once in a while rather than my transmission components.

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tfdeputydawg
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Re: Tire Cupping

Postby tfdeputydawg » Wed Sep 30, 2015 5:58 pm

WingAdmin wrote:This is a very accurate article describing the cause of various types of tire wear. The one thing he states that I totally disagree with is his insistence that downshifting is not a good practice. He says you should just hold the clutch in and let the engine idle as you shift down through the gears, to save your rear tire, and reduce driveline stress.

However having your engine at idle when shifting down at speed can wear your transmission due to the difference in speeds between the input and output clusters. In addition, if you suddenly need to get out of an emergency situation, you first have to rev up the engine, match the engine speed to the rear wheel speed, then let out the clutch, and hope you matched the speed correctly. If you haven't matched it, you run the chance of locking the rear wheel.

I prefer to downshift, have my engine connected to the rear wheel so that I can simply twist my throttle to add power if I need it, and change my rear tire once in a while rather than my transmission components.

+1 on that. I always down shift and raise the RPM as I let the clutch out.

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maintainer
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Re: Tire Cupping

Postby maintainer » Wed Sep 30, 2015 6:17 pm

WingAdmin wrote:This is a very accurate article describing the cause of various types of tire wear. The one thing he states that I totally disagree with is his insistence that downshifting is not a good practice. He says you should just hold the clutch in and let the engine idle as you shift down through the gears, to save your rear tire, and reduce driveline stress.

However having your engine at idle when shifting down at speed can wear your transmission due to the difference in speeds between the input and output clusters. In addition, if you suddenly need to get out of an emergency situation, you first have to rev up the engine, match the engine speed to the rear wheel speed, then let out the clutch, and hope you matched the speed correctly. If you haven't matched it, you run the chance of locking the rear wheel.

I prefer to downshift, have my engine connected to the rear wheel so that I can simply twist my throttle to add power if I need it, and change my rear tire once in a while rather than my transmission components.





Exactly right,
I have listened while other rider's spoke strongly against downshifting and insisted their freewheeling technique was the correct and the proper way to decel.
Chicken feather's,
I have always accelerated and decelerated make full use of my torque and compression. To coast to a stop with the clutch pulled in just seems very disconnected, and I won't do it.
1982 GL 1100 Interstate SOLD
1977 GL 1000 Standard (naked can be good, who knew?)

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Re: Tire Cupping

Postby NVSB4 » Wed Sep 30, 2015 6:52 pm

maintainer wrote:To coast to a stop with the clutch pulled in just seems very disconnected, and I won't do it.


I always adjust the throttle (upshifting or downshifting) according to the next gear.
If I'm stopping, I'm usually am going slow enough that I'm pulling in the clutch a little after I hit the brakes.
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tktrnr
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Re: Tire Cupping

Postby tktrnr » Thu Oct 01, 2015 6:02 pm

Downshift if you always want to be in control.

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spiralout
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Re: Tire Cupping

Postby spiralout » Fri Oct 02, 2015 1:18 am

I'll admit, I haven't read the complete article yet but on the rear center tire wear section guy says "...because acceleration, engine braking* and real braking scuff stuff off the upright rear tire. Each time you downshift to engine brake, upshift and release the clutch, roll on the throttle or roll off the throttle, you will scuff the rear tire at the contact patch." then went on to say in the engine braking footnote how horrible it is to engine brake and you'll lose thousands of miles of tire wear by doing it.
What he failed to say, following the logic of his first statement is "Each time you downshift to engine brake, upshift and release the clutch, roll on the throttle or roll off the throttle, or use the rear brake you will scuff the rear tire at the contact patch."
In my experience, from my riding style, the majority of the times I'm using the engine to brake is when I'm riding leisurely, slowly rolling up to a stop sign or light. If I'm riding aggressively, I slow later and use the brakes much harder and put more stress on the tires than I normally would. That make sense?




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