Has anyone heard of the rolling resistance ratings that are supposed to be California law as of July 2008? Supposedly all states were to benefit in that we could see the rolling resistance on all tires without paying for the info (consumer reports). Just wondering if anyone has heard anything more.

 

Haven't heard, but this would be an excellent move. All tires do not roll equally... especially if underinflated.

 

There is such a move. GM has already instituted their Cavaliers, whatever, so they could advertise higher mpg.
Right now only the tire manufacturers know. There is opposition from Prius because many buyers complained about the low cornering capability of the low-rolling resist tires and now Toyota offers a 'touring tire' option.
There's no tree lunch. Lower rolling resistance for 2 mpg better also means lower corneringf speeds, in my opinion not a good tradeoff.
Maybe if I owned a Suburban.

 

I had hoped the new rating system would give us better data to choose the best compromise. I don't want to give up handling either. I'd still like better mileage but not to the extreme that the prius's tires took it.

 

I have heard bad things about the handling of Prii, but wasn't sure if it was due to the LRR tires or just the softness of the car itself.

I am very happy so far with the handling and rolling resistance or the stock Dunlops on the Fit.

 

The prius tires get poor handling ratings. That's why I hoped ALL tires would be rated for rolling resistance (as of July 08) so we could choose a compromise that didn't adversely affect handling too much. I like the handling of the stock dunlops, so far. I've heard they wear quickly and I just hoped to get better mileage with the next set. My fit just hit 6K so the tire purchase won't be for a while.

 

Although not the ratings I had hoped for this "green report" on low rolling resistance tires was interesting.

http://greenseal.org/resources/repor...resistance.pdf

 

Based on recent tests with a Ford Escape hybrid as mpg increased from 17 to 19 mpg with less tire rolling resistance the wet braking distance increased from 150 to 210 feet from 60 mph.There is no free lunch.

Blame it on harder tread compounds needed for low rolling resistance that don't grab the road with more 'tentacles' of rubber that interlock with road roughness. The softer the rubber the better they create tentacles and of course if you stress them they break off, hence shorter wear life. Those tentacles are adhesion and adhesion is braking ... and acceleration and cornering.
Its a lot like autocrossing on snow tires vs Hoosiers.

Here's an experiment to demonstrate. Get some soft urethane foam and press it into a coarse file. Note how it presses 'tentacles' into the file. Now push the foam across the file. Shreads the urethane pretty good. doesn't it. Some effort needed but once it fails very little.

Now get a piece of hard rubber and do the same. Hard to push it across the file even though it too has 'tentacles, just not as deep. Much more effort.

Now get a piece of smooth hard steel and repeat. no tentacles so its easy to slide that steel across that file.
The same thing holds true for tires. The steel will last a long time by comparison but hardly useful to stop or corner a vehicle.

 

I never expected a "free lunch". Higher wear ratings will, of course, mean harder rubber compounds. Usually when you gain one thing something else is sacrificed. No free lunch! I won't need tires for at least a year but I want as much information before the time comes so as to make an informed choice. I would not buy prius tires, escape tires or buy exclusively based on rolling resistance ratings. I want as much information to choose the best compromise for me. I've not seen the California dictated rolling resistance ratings as yet but hope they will be available to the general public in the future.