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Old 04-13-2009, 04:48 PM   #22 (permalink)
Ernie Rogers
Ernie Rogers
Join Date: Feb 2008
Location: Pleasant Grove, Utah
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Originally Posted by CapriRacer View Post
. . . I think tread rubber with good hysteretic properties tend to be soft (I am going to check on this, but I am under the impression that good wearing tread rubber tends to be "hard".)
I definitely agree with this statement, although I allow that there may be exceptions. (Example: tombstones are routinely cut by sandblasting. rubber is placed over the hard stone where they don't want to cut. The hard stone is cut, but the soft rubber isn't.)

I have a high regard for CapriRacer's knowedge and engineering skill. We can just admit we disagree on a few points now and then. But, notice that this question of how rubber properties and contact patch affect Crr is mostly academic. We should just judge tires by the Crr and forget much of the rest.

My advice to Harry is to use 205/60R16. That was the middle choice for size increase, as I recall. This is expected to give good benefits with much less risk. So, Harry, ask around and make your best guess. I would buy from a local dealer, and I would ask, "do these tires have a customer-satisfaction guarantee?" Most tire companies will let you return tires within 30 days for a full refund. (You may get stuck on the local service, like balancing.)

I would carefully check mileage before changing, and after. And, you can bet I would return tires that don't improve mileage. (I've done it before.) Remember that you must check mileage under identical conditions as much as possible. Adjust speedometer readout downward as needed and use odometer corrections.

Ernie Rogers
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