B arry's T ire T ech

This is a series of articles on the technical aspects of tires, their care and usage.

My primary purpose in these articles is to help people understand tires and thereby reduce the risks we all face every day.

..........and since tires is just about the only thing I know about..........

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Barry's Tire Blog:

This page is going to a place where I can comment about stuff - usually tire related - and not worry about documentation, precision, accuracy, etc.

If you wish to comment on my comments (Doesn't that sound funny?), email me and if they are good, I'll post them.


28 Mar 2010

As a tire engineer, I am frequently amused by the statements made about tires, tire wear, and such related stuff. “Amused” meaning that there are a lot of myths and old wife’s tales out there – and they get repeated. So in an effort to dispel those myths, I offer the following:

1) As a set of tires wears, it is subjected to a certain amount of misalignment. This misalignment causes the tire to wear irregularly. The further the alignment is from “ideal”, the faster this irregular wear shows up.

    First, the “ideal” alignment might not be what is published by the vehicle manufacturer. As an example, some manufacturers want their vehicle to handle well, so they’ll dial in camber. This is not good for tire wear.

    There are other issues concerning the published alignment specs, but it is difficult to enumerate them all.

2) The alignment specs published include a tolerance – a range of acceptable values. Not only do I think the tolerance is too wide, I also think the tolerance is arbitrary.

    It isn’t the case that an alignment “IN SPEC” is 100% OK. This is a matter of degree. As I said above, the further the alignment is from “ideal”, the faster this irregular wear shows up.

3) Tires do have sensitivity to misalignment – some tires being more sensitive than others. The thought I want to convey here is that:

    a) The cause of the irregular wear is the misalignment

    b) The tire’s sensitivity decides whether the problem is big or small.

So I think the point would be to keep the vehicle in alignment and there will never be a problem.

4) OE tires should not be expected to last more than 30K miles. Because of the way this is done, OE tires aren’t oriented towards wear.

    Further, In spite of what the warranty says, OE tires aren’t going to reach the mileage indicated. Which brings me to:

5) Mileage warranties aren’t what they appear to be on the surface. They aren’t a guarantee that YOUR tires will achieve that mileage. So first, the science part:

    Tire wear is complex and there are a lot of factors that affect what a tire ultimately delivers. Most of those factors will overwhelm the “miles” part of the equation.

    Further, OE tires not only don’t have mileage as a design feature, they are basically designed by the vehicle manufacturers – who abdicate their responsibility by not providing a warranty on the tires. They throw it back to the tire manufacturers.

    What this means is that the tire manufacturers are stuck with tires that they didn’t design, didn’t make a lot of money on, and then are responsible for a property that the general public feels is important, but wasn’t considered very important during the design process. There are only 2 options available to the tire manufacturer:

      a) Persuade the vehicle manufacturer to give tire wear a much higher priority in the design stage of the process – something tire manufacturers have been galactically unsuccessful at.

      b) Refuse to participate in a particular program where tire wear is not a major consideration. This is fraught with problems for the tire manufacturer. Not only do vehicle manufacturers not like to be told what to do, they also feel that suppliers should put forth a reasonable effort to comply with any requests that the vehicle manufacturer tells them to.

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