So another thread got me thinking.... I had heard a rumor that one of the trade offs for LRR tires are reduced tread expectancies... So, I did some research and here's what I found.
There really isn't a link between UTQG Tread Life ratings and RRC. HOWEVER, when tire types/sizes/etc. were disaggregated for 15" wheels and a speed rating of S or T. There was a WEAK relationship between Tread Life and RRC. That relationship was that LRR tires have less tread life. Again, a WEAK relationship. Jump to pdf page 114 for "UTQG Tread Wear Grades and Rolling Resistance" - link below. I guess the rumor had a scrap of truth - but nothing to stop someone from buying LRR
Other interesting relationships.... Remember that these compare tire ratings of around 200 different tires - this isn't point of research empirical testing (it's based off of standard testing data), this is statistical analysis.
Interestingly, there's a potential that LRR tires may not have the lowest RRC over their whole lifetime. That is, potentially a non LRR may have a better lifetime RRC as excess tread is worn down resulting a lower instantaneous RRC. Again, that's a possibility
Here's a useful chart that I haven't seen before -- it's in that pdf though....
UTQG Wet Traction Req's
Grade Sliding Friction Coefficient (Asphalt) Sliding Friction Coefficient (concrete) % NHTA tires with rating
AA >.54 >.38 4
A >.47 >.35 78
B >.38 >.26 18
C <.38 <.26 <1
Personally, I have Michelin Pilot Exalto A/S. The reason I didn't go for a LRR tire - my location. Too much rain for too much of the year - so wet traction is a big deal for me. The only thing I don't like about them is that they are directional - so I can't cross rotate my tires. But, that's a trade off for better wet traction.
Any way, there's some good information in there
Time is the best teacher. Unfortunately it kills all its students.