Old 08-06-07, 12:02 PM
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Campag4life
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Originally Posted by TJHOO View Post
1-Is it generally true the grippier a tire is, the more rolling resistance it has?
2-Is it generally true the grippier a tire is, the less harsh a ride it yields?
3-Is it generally true the grippier a tire is, the less durable it is?
Grippy generally doesn't mean 1 or 2. Grippy generally means soft compound and that means less durable or 3. Rolling resistance or #1 is generally a function of carcass stiffness which is mostly a function of TPI. (Threads per inch)
The more the TPI, the easier it is for a carcass to displace itself...what contributes to rolling resistance and also btw a more compliant ride or #2. The problem with high TPI, is opportunity for road ingression...more holes in the carcass due to more threads. So its a tradeoff generally between rolling resistance and puncture resistance. Out and out racing tires with high TPI count tend to be faster. Grippy has to do with the softness of the tire compound which portends greater wear.
As mentioned, the Michelin PR2 with 127 TPI is a wonderful balance between rolling resistance and puncture resistance. The downside if any is wear due to its upside with is grippiness which is due to it relatively soft tire compound. Tire selection is a balance and mostly a tradeoff. You need to pick the tire based upon what is important to you. No single tire is all things of course. HTH.
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