Quote:
Originally Posted by rob.e
What confuses me is that the BMW tyre (bridgestone ecopia EP500) gets a fuel economy rating of only "B" (eu tyre labelling) which i was surprised about given how skinny it is..
Tyres i have on my honda are way wider (225/40 18) and are rated better for fuel economy - they are "A"; pirelli p7 blue.
How is the pirelli better than the skinny super-eco bmw bridgestone? Or am i missing something?
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What you are missing is that the physical dimensions only play a minor role in RR - and width is just one of 3 dimensions. You didn't say, but I'll bet the BMW tire you compared to your Honda tire is actually SMALLER in load carrying capacity - and more load carrying capacity = lower RR (all other things being equal!).
Then there is the issue of the tire itself. The tread compound plays a HUGE!! role in RR. It just may be that the Pirelli is just more up to date than the BS. (Just an FYI: Once a tire has been qualified at an OEM, the OEM doesn't want it to be changed. If the BS tire was qualified a number of years ago, it might be stuck in a timewarp.)