Re: [ST] Tire Pressure on a Worn Rear

[Blake Sobiloff <sobiloff@xxxxxxxxxxxxxx>]

On Mar 2, 2004, at 3:17 PM, Craig Tate wrote:
> The question is, "what part of the tire will be worn when the tire is 
> under inflated?"  Rather than take my advice, or the advice of others 
> here, look at any tire manufacturer's web site.  You will see that 
> under inflated tires wear on the shoulders, over inflated tires wear 
> in the center.

That is certainly true for automotive tires, but automotive tires have 
a completely different tread profile.  It is flat, quite unlike a 
motorcycle tire profile which is rounded to allow for the lean angle a 
bike is capable of (and a car, obviously, is not).

(The flat automotive profile is prone to arching upward of the center 
tread when under-inflated, causing the outside shoulders to have 
greater contact with the road and wear faster.  Similarly, when 
over-inflated, the middle of the tread in an automotive tire will wear 
faster because the center is arched downward, lifting the shoulders of 
the tread.)

I checked Michelin's and Dunlop's motorcycle web sites, and aside from 
articles on cupping, could find no articles to support your assertion.  
I'd be happy to read the ones you found if you'd post the URLs.

Here are a couple of articles I found that seem to disagree with your 
assertion, too:

Here's what an interview 
<http://www.motorcycle-usa.com/Article_Page.aspx?ArticleID=442&Page=1> 
with a Dunlop person (Mike) had to say:

"But the most important factors affecting tire life is controllable by 
the rider. The number-one factor that leads to premature tire wear is 
underinflation. Mike Manning travels to motorcycle events around the 
country with the Dunlop Tire Inspection Crew. They provide tire care 
and free tire inspections to all motorcycles. He tells me that 85% of 
all tires that they check are underinflated. Not only is that dangerous 
for the bikes handling, but it can shave 20 to 40% off the tires life. 
Mike recommends that you look at the tire manufacturers suggested tire 
inflation pressure rather than the number the motorcycle manufacturer 
puts in the owners manual, to get the optimum performance from the 
tire. You can safely inflate the tire up to the maximum tire pressure 
shown on the sidewall of every tire, so it offers more load capacity 
when you are riding with a passenger and luggage."

This is what Michelin has to say about under-inflation:

	<http://motous.webmichelin.com/tires/safety.htm#under>
- --
Blake "Dawgbert" Sobiloff <sobiloff@xxxxxxxxxxxxxx>
President, Triumph Sport Riders Assoc.
San Jose, CA  (USA)


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