Quote:
Originally Posted by ConnClark
Apparently you haven't been following the discussion.
...........
|
Unfortunately, I have been and I wanted to make sure eveyone avoided the trap of 2 dimensional thinking - especially the misconception that hardness and rolling resistance were somehow related, similar to the way it is commonly misunderstood that hardness and traction are also related.
This technology triangle is one of the design compromises that tire engineers have to face, especially when designing tires for the OE market. Vehicle manufacturers are keenly aware that tires have rolling resistance and that using low RR tires can not only improve a vehicle's EPA fuel economy ratings (a selling point), but also provide some relief in the development of a vehicle when the vehicle engineers have difficulty meeting their objectives, such as weight, energy consumption, etc.
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.
But tires designed for the replacement market are less subject to pressure of fuel economy. Most consumers feel that tires are supposed to deliver good wear characteristics - with traction and rolling resistance being very far down the list of desireables. As a result, most replacement market tires do not have good RR properties - and if there is a compromise to be made, it is between wear and traction - which fuels the misconception of hardness vs traction.
So just a word of caution.