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Old 02-21-2010, 06:36 PM   #67 (permalink)
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Originally Posted by CapriRacer: The problem is that extremely low RR tires tires also don't have great traction and / or wear life. This is one of the reasons one hears lots of complaints about these properties on tires supplied to new vehicles. It is commonly thought the cost is what is driving this, but that is not the case. It's this technology triangle.

Miller: A different tread compound is used in each tire toachieve lower rolling resistance and better fuel economy than on standardtires. A fuel-efficient compound typically has a higher rebound value. In thepast, rubber compounds with this property might not wear very well, butengineers have come up with ways to improve rolling resistance without asignificant loss in the other properties that are required of a truck tire.
Nokian uses the cap technology described here:

Graves: Some compounds, especially those incorporatingsilica or using special formulas that combine natural and engineered-structuresynthetic rubber, can affect rolling resistance significantly. In some cases, atwo-layer, or “cap-base” tread can be used. The cap compound, which is chosenfor high resistance to abrasion and high traction characteristics, tends togenerate more heat, so a base layer with a cooler-running compound is chosen toprotect from heat buildup. The result is lower overall tire temperature forlonger casing life, which also means lower rolling resistance and better fueleconomy because less energy is wasted as heat.

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