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[dsn_klr650] what causes tire cupping?
Posted: Tue Jun 13, 2000 4:12 pm
by bill e goat
is cupping
> pretty bad.
Do they need to
> be put on a certain way so they don't cup? Is there
> anyway to get rid of the cupping, without buying new
> tires?
Motorcycles just cup the front tires.....they just do
it. Some do more than others, but they seem to all do
it....or at least every one of the twenty or so I've
had....it's just a matter of degree. My KLR cups its
front tires as well....It has cupped a Dunlop K750, in
about 2500 miles, and three Maxxis 6006s in the other
12000 miles it done on pavement and dirt. They just
do it.
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[dsn_klr650] what causes tire cupping?
Posted: Tue Jun 13, 2000 4:47 pm
by Tom Myers
> is cupping
>> pretty bad.
>Do they need to
>> be put on a certain way so they don't cup? Is there
>> anyway to get rid of the cupping, without buying new
>> tires?
>
>Motorcycles just cup the front tires.....they just do
>it. Some do more than others, but they seem to all do
>it....or at least every one of the twenty or so I've
>had....it's just a matter of degree. My KLR cups its
>front tires as well....It has cupped a Dunlop K750, in
>about 2500 miles, and three Maxxis 6006s in the other
>12000 miles it done on pavement and dirt. They just
>do it.
"They just do it......." can't really say it better, but an engineer
will always try, won't they?
Here is a shortened version of the enginerd explanation.
Every time the tire goes around, the pavement slaps it. This
rhythmic slapping creates a "standing wave" near the contact patch on
the pavement. The radius of the "cup" might be related to the radius
of 'bend' created as the tire tread bends from "round" to "flat" and
returns to "round" again every time its slapped. The tire probably
scrubs pretty hard on the pavement as it's being bent form round to
flat.
You can try higher tire pressure or longer wheelies. Best to try to
forget about it or the enginerds won't give you any peace.
Tom
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[dsn_klr650] what causes tire cupping?
Posted: Tue Jun 13, 2000 5:03 pm
by k650dsn@aol.com
In a message dated Tue, 13 Jun 2000 5:48:50 PM Eastern Daylight Time, Tom Myers writes:
>>
Yep, even when they don't know the answer.
I've noticed that it is worse on thumpers. I know a guy who road a, ahem... bike from Bavaria, that cupped it's front tires and would not accept the answer that that was normal. When all was said and done, his dealer had ordered 3 new front wheels and was stuck with them and the guy basically made them take the bike back.
I know you aren't supposed to do this, but on non-directional tires like the MT21, I just flip the tire around. It rides pretty rough for a while, but you get your money out of it.
Gino
[dsn_klr650] what causes tire cupping?
Posted: Tue Jun 13, 2000 5:15 pm
by tebklr@aol.com
Ah yes, but the answer is...........uneven pressure distribution on the tread
pattern. The areas of higher contact pressure with the pavement scrub more as
they deform from a rounded profile to the flat contact patch as they rotate
on to the pavement (the pavement does not "slap" the tire). Ergo, more wear,
hence cupping. It's a trade off in m/c tire design, and one that m/c tire
engineers spend A LOT of time trying to manage. After all, the tire companies
definitely want you as repeat customers. The car guys have it a bit easier;
with their essentially "flat" profiles, their tires only have to deform
longitudinally (with a lot less potential for cupping), but m/c tires must
deform longitudinally and laterally.
How's THAT for the engineering side?!!?!?!?!? HA! Tom
>>
Yep, even when they don't know the answer.
>>