RRC and Tread Wear

[trebuchet03]

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.

Bigger wheels = lower RRC
Higher Wet Traction Rating = higher RRC
More Tread = Higher RRC
Less Tread = Lower RRC
Higher Speed Rating = higher RRC

The above isn't necessarily a rule. It just means that the cost of development is very high to satisfy the small demand for high efficiency high speed tires


http://onlinepubs.trb.org/onlinepubs/sr/sr286.pdf

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

[bowtieguy]

very good info. since we both live in the same general area, safety(wet traction) is also a huge consideration for me.