OzSTOC
Honda ST1300 Section => Tyres...to suit your ST1300 => Topic started by: StinkyPete on September 05, 2013, 11:20:26 PM
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What is the cause of scalloping on a rear tyre? I am running a Michelin PR2 at 42psi on the rear and it is showing significant scalloping.
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The link (below) from a previous post might explain this http://ozstoc.com/index.php?topic=3525.msg35769#msg35769 (http://ozstoc.com/index.php?topic=3525.msg35769#msg35769)
http://www.rattlebars.com/tirewear/index.html (http://www.rattlebars.com/tirewear/index.html)
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.
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Sometimes a bit more pressure in the rear might reducing the cupping a bit, but as the PR2 has a softer compound on the side tread it is prone to cupping. The more corners you ride, the worse it gets. I have had tyres where the side tread goes before the middle.
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Ridding against a side breeze for a long time will also do it
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Yeh I had a significant side breeze al the way from Middleton to home. I got sick of riding on a lean for hours on end. There was noticeable wear on the right side of the tyre after 10 hrs of side breeze :-[
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Crossing the bore got me a new tyre at Port Augusta
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This isn't directly related to scalloping but....
There is an article I read that talks about wear on tyres and how the different radii of corners depending on turning left or right can affect the amount of wear on the side. I have done a thought exercise and it is amazing just how much further the right hand side of the tyre travels compared to the left.
If a corner has a radius to the middle of the inside lane of 6 metres and the outside of lane of 8 metres the difference in distance travelled to an equal point on the road for a 90° turn is about 3 metres (9.4m against 12.5m). The difference equates to better than 30% more for the right hand side which is a hell of a lot between left and right turns.
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Which is why I always give it more throttle on left turns to try to even the tyre wear.
:bl11