Tread Wear Rating and Rolling Resistance
 

I've been reading a report suggesting higher tread wear ratings corresponds to higher rolling resistance, but only in passing. Does anyone else have any source material on this?

Evidently ~5% of vehicles have ratings between 600 and 800 (the highest grouping), and my former tires were 680, so if this were true that might explain my big MPG jump with the switch the LRRs.

Thoughts?

Intuitively, it seems rather strange to think that a tire with a higher treadwear (and thus, longer life, partly due to lower friction coefficients in the rubber compounds) would have a higher rolling resistance... but stranger things have happened.

I skipped ahead in the report to some of the results and it seems to suggest that in empirical testing there is no real connection between tread wear rating and RRC, but it seems considerably more complicated than that...

Since it's a rather long report, I will wait to finish up and then report back :p

Where's the report?

trb.org/publications/sr/sr286.pdf

Have fun

Good find- yes, it's a fun one. :thumbup:

Validation of worn-out tire reduced r.r.! They say 20% reduction.

It appears the good stuff starts on pg 122.

Hysteresis is the biggie for losses. Deep treads = more hysteresis.

Tread wear ratings don't translate into miles of life. Tires with lower tread wear ratings have shallower treads, which equals lower r.r.

However, tires with deep treads, when worn to the shallower depth, can be said to have the same r.r.

First, it is widely known within tire engineering circles that Treadwear, Traction (especially wet traction), and Rolling Resistance are the three legs of the technology triangle when it comes to tread compounds. Improvement in one property results in degradation in another.

I go into it a little deeper here:

Barry's Tire Tech

And RR is pretty much about tread compound: The amount and its properties.

Worn tires do indeed get better fuel economy than new ones - all other things being equal.

But tires designed with RR in mind - like Original Equipment (OE) tires - can have fairly low RR values compared to replacement market tires. But the tradeoff is traction and/or wear.

So, no, Frank, low RR tires do not always have thin treads - it's a bit more complex than that.

I was extremely disappointed in this report. While they may have tested some tires for RR, they did not test tires for traction and treadwear. I can understand that treadwear is expensive and highly variable - and that perhaps cost was a factor - but they didn't realistically deal with the marketing nature of the UTQG treadwear rating.

I was also disappointed in Marion Pottinger's stance within the committee. I sensed that there was a political agenda at work - that encouraging the concept that improvements in RR can come without sacrifices in traction and/or wear would result in more testing for those companies that do this type of testing - and guess what Marion Pottinger does? M'gineering is a testing company.

Bottomline: I found nothing of value out of this report and found much to be critical about. I think this report slowed the progress of tire technology rather than encouraged it.

See page 26 of this report.

Even though a low UTQG treadwear rating doesn't necessarilly mean LRR, you will see the lowest RR tires of the bunch have a relative low treadwear rating, and most notably, that no high treadwear tire has low rolling resistance. Just look at the lowest point for each treadwear rating.

weight rating coincides. the tire squish is the footprint..could be flat footed and as hard as a T-rated at the same time. I have learned this recently. I have t-rated that looks to have gone thru h*ll, random tire deflatings, by nature..the whole time it was the weight rating...on extremely hard tread that could last the torture forever.

the two digit number .. if AWD, half the weight of the car on one tire is a good call. I need "91" for an old sube with lockup diffs, as example. The FWD machines get away with just about everything but longevity. A good weight rating will help make a stiff ride, as it does not need as high one. And then there is the brand name game..are you really getting the rating written?

Interesting. Do you have more info on the connection between RRC and traction?