[CapriRacer]

cfg83,

As you found out, unless you compare the same EXACT size, you'll have problems drawing conclusions about the tread pattern. It is fairly common for small widths to come in 4 rib patterns where wider width tires will have 5 rib - and I've even seen 6 ribs used for extremely wide tires.

Second, OE tires will break up the pattern within a tire line. The vehicle manufacturer may demand a particular "look", and that may result in more groove width (or less!), more sipes per inch (or less!), and the pattern would be adjusted according - and slightly different than the "standard" for the rest of the line. - and, of course, each vehicle manufacturer would have different specs and desires, so the resulting patterns would only resemble one another.

- BUT -

The most important thing in rolling resistance is the tread compound. The tread pattern hardly has an effect on RR at all (except for the amount of rubber used). Simply changing the tread compound can have a profound effect - up to 60%. I can easily imagine that these tires just benefitted from an evolutionary development in rubber chemistry as have many of the other recent new offerings from other tire manufacturers.

BTW, Rolling Resistance is traded off with Treadwear and Traction (especially wet traction) within tread compounds. Tires with great RR will have poor treadwear or traction. The trick is to select a tire that has a good compromise that fits your needs.