Strange wear pattern on front tire

 Hi all,

Not a problem (I think), but I am curious.

When I looked at my VF400F while the sun was about
to set, I noticed a strange (but regular) series of shades
on my front tire.

The tire is a Dunlop Arrowmax K625A, mounted correct,
and the wheel is balanced. There is no vibration on the
handle bars too.
The tire is about halfway it's life, about a year old
(I don't take a note when I buy a tire), it is not dried
out, and never repaired.
I ride the bike on average 4 times a week, which
is approx 400 miles each week.

Note that the pattern on my tire differs from the
arrowmax K625A shown at the dunlop web site,
so I describe the pattern below.
The pattern on the rubber looks as fat arrows, split
over the full length from point thru shaft in a straight
line, so it looks as if there are a series of split arrows
on the tire. The arrow-points hit the tarmac first,
which is the way it should be.

Arrows are 3" long, the head is 2" wide, 1" long,
and the shaft is 2" long and 1" wide.

The strange wear pattern that I have is on
the last part of the shaft, about an inch (25mm) long,
and that shaft end is about 1/32'' (1 mm) lower than
the next arrow point (which comes about 1/16" (2mm)
after that lowered shaft end).
So the shaft ends all wear faster than the rest of the
arrows. This I can imagine because the shaft is
smaller than the arrow heads. But.......

a) The strange thing is that only the shaft ends
   of the left 'splitted' arrows are lower. The right hand
   is still at the same level as the rest of the arrow.

b) The 'worn out' shaft end dives neatly (not abrupt)
   with a curve to that lower position. And all of
   the arrows have the same wear of that left shaft
   end.

Now, I am a front breaker (rear doesn't do much)
and the anchor plate of the brake holds on to
the left front fork. So I thought that that could
be the reason.

Wrong tire pressure would affect both shafts, not
only the left hand side (I suppose). Could be
a worn out shock on the left side (I had that for
a while), but I don't know.

But maybe somebody out of cycles.tech-land has
seen this before and can enlight me on the cause.

Rob.

 oldgeezer wrote:


You're talking about scalloping.

You're pushing the front tire harder as you corner to the left,

The tire actually slips more and more sideways as you increase lean angle,
tearing miniscule bits of rubber off one edge of the tread blocks.

The harder you corner to the left, the quicker the tire will exhibit this
kind of wear.

You don't corner as hard to the right as you do to the left, so you rarely
see scalloping on the right side of the tire.

Taller tread blocks will show this wear more than lower tread blocks.

Treadless slick tires don't scallop at all.

Then there was the BMW rider who was complaining about *even* tire wear only
on the left side of his
telelever-equipped machine.

They didn't scallop because his front end was so compliant.

But he thought his tires simply shouldn't wear out on one side.

He was so p*ssed off at BMW for inventing the telelever fork.

You can never get front tires to stop scalloping by adjusting tire pressure,
if the motorcycle is comfortable and handles well enough with the pressure
you're using now, just accept that scalloping is going to be worse with some
tires and others.

Tire scalloping is less noticeable on rear tires, but it still occurs. One
Gold Wing rider was talking about changing his swing arm bearings because he
suspected them of causing the scalloping.

He was at a total loss to understand the interactions between pavement and
tread blocks.

--
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http://www.motorcyclekb.com/Uwe/Forums.aspx/tech/200705/1

 oldgeezer wrote:


<v.big snip>


Do your roads have a camber on them?


Cupping, I believe it is called. If your road has a camber, and you ride on
right, the left of centre does indeed wear in a different pattern to the
right.

My current bike is displaying similar right of centre, as have many tyres in
the past.

HTH

 

Ignore the reams of crap from Albrecht, saying you ride harder in
left-hand corners than right. The answer is, quite simply, road camber.


--
 BMW K1100LT  750SS  CB400F  CD250  Z650  SL125
 GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
 BOF#30 WUSS#5  The bells, the bells.....

 The Older Gentleman schreef:

I would believe Albrecht, because his explanation seems logical,
if it wasn't a fact that I lean over in right hand corners more than
in left hand corners. I really do. Maybe that is caused by the fact
that there are more right hand corners (in and out highways) in
The Netherlands than there are left hand corners. So I am
more confident because I've done right_hand much more times.
There used to be one left_out of the highway near The Hague,
but it was changed because it created a lot of accidents when
people on the slow lane (right) had to switch to the left lane
(high speed) in order to get off the highway.

So it could be road camber. But I ride for about 50 years (of
which 40 years daily) and never saw anything like it.
And my other VF400 (I have two 'brothers' that differ the
last digit in framenumber, engine-number and license plate)
with a Firestone Battlax that is almost at end_of_life also
seems to wear out evenly. But the profile of the Battlax is
totally different. That may help.

Thanks for your answers.
Rob.