[ST] Tyre cupping

["Keith Tynan" <keith@xxxxxxxxxxxxxxx>]

Mainly for those of us in Blighty, who haven't a clue what this strange term
"tyre cupping"  means, I've recently had a few exchanges with Allan
Wittmeyer [mailto:awittmeyer@xxxxxxxxx] of Goodyear US (allied with
Dunlop)...

BRG1> I'm a subscriber of several global motorcycle lists, the North
BRG1> American members of which frequently refer to "tire cupping".
BRG1> Despite requests, no-one's been able to come forward with a
BRG1> definitive explanation of this term. Even your FAQ article
BRG1> doesn't make clear whether it's synonymous with "uneven wear"
BRG1> or a separate feature.

AW1> True "Cupping" in a tire happens on both sides of the tread.
AW1> Some people say it's "Uneven wear". Well uneven wear is when
AW1> one side of the tire is wearing differently than the other.
AW1> "Cupping" usually occurs on the front more than the rear. It's
AW1> basically from low pressure, or excessive front braking. The
AW1> load surge of the bike causing the front tire to flex more
AW1> which causes the tread rubber to wear off in a "cupping"
AW1> fashion on both sides. This may not be the most scientific
AW1> explanation, but I hope it helps.

BRG2> What you seem to be saying is that, viewed in cross-section,
BRG2> different parts of the tread will wear at different rates,
BRG2> giving a slightly concave look to the tyre surface (though
BRG2> the wear pattern may be symmetrical about the tyre
BRG2> centreline). Is that correct?
BRG2> Would I be correct in presuming that this term is only
BRG2> applies when the concave wear is apparent away from the
BRG2> centre of the tyre; I would term wear at the centre
BRG2> 'flattening'.

AW2> You've got it pretty much understood.
AW2> It's just a matter of trying to stop that type of wear on
AW2> your bike. Most bikes with bigger front fairings seem to
AW2> have more of a problem with cupping because of the load
AW2> surge toward the front is much easier applied.

HTH

Regards,
- --
BRG
mailto:keith.tynan@xxxxxxxxxxxxx
http://myweb.tiscali.co.uk/keith.tynan
'00 BRG Sprint ST 'Wolfram'



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