OEM tires more efficient than same aftermarket replacement
 

I know this has come up before, but just wanted to add this to the forum for posterity:

On new cars...
From Canada, Europe develop tire ratings to reflect fuel efficiency

Also of note, repeating what has been said elsewhere on the forum:

I tend to think that tires with thinner sidewalls and less tread are going to be cheaper, and that's more of a motivation for the manufacturers to install them than to be "environmentally conscientious".

To me "eco" driving is more about being "eco"nomical than "eco"logical. If the tires have less tread, they aren't going to last as long and with what I have to pay to have tires installed and balanced, it seems that any money saved on fuel will be spent on tires.

I'd like to find a set of summer wheels to install some high mileage dry weather tires, but here in the high mountains, weather can change at any time of the year, and you really do need that tread in order to safely get around.

My thoughts exactly. They're going to put on the cheapest thing possible that meets safety standards. So anything you buy that's not the original equipment tire is going to be better.

Thinner walls and less tread means less weight, right? So do low RR tires have more rotational mass?

...the OEM Goodyear RS-A Eagles 205/55R16's on our 2009 Vibe have crr = 0.00915 (per NHSTA document), and they've been used as "base" OEM tires on the Vibe since it's original introduction back in 2003.

...not the greatest, but certainly not the worst by far.

I wouldn't accuse (m)any manufacturers of being "environmentally conscious" solely out of the good of their hearts, but don't forget they also have to meet CAFE fuel economy targets, or pay penalties.

As with any cost vs. fuel consumption issue, you can be pretty sure there's a spreadsheet on the bean counter's computer just about tire selection!