Why the low rolling-resistance?

Note, however, that that page refers to the 2001-2003 Prius. All references on that page to the OEM tires refer to the tire that came with the Classic Prius. The '04/'05 Prius comes with a much better tire (though still not as good as many that are available).

The general info about tires on that page is good. But all references to the original tires are obsolete if you are driving a new Prius.

 

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One property would be stiff sidewalls. A tire with flexible sidewalls (or an underinflated tire) will deform its sidewalls as it rolls. It takes energy to flex the sidewall as the tire rolls, so a car on tires with stiff sidewalls takes less energy to push down the road. One way to give a tire stiff sidewalls is to design it for higher inflation pressures. My guess is that stiffer sidewalls is the major contributor to low rolling resistance.

Tire compound probably has a slight effect. Since car suspensions are designed with a degree or two of toe-in, the tires are really scrubbing all the time. A harder compound is going to have less friction as it scrubs across the pavement, so it should roll easier.

 

And yet the Potenzas on the Classic Prius were notorious for wearing out fast.

 

I just picked up my 2005 with p185/65 R15 Goodyear Integrity tires. My tire dealer says those are not "LRR" tires. He was unable to find LRR tires in that size on any of his lists. Seems strange the car would not come with LRR tires. I've read the MPG tests are done with LRR & that's why the dealer has to supply them. Any comments? My owners manual says 35 PSI front/33 rear. The dealer had 40psi for all. Should I run with the higher pressure or will it wear out the tires in the middle prematurely?

 

The 04/05 OEM tires are not formally "LRR".

For some reason, manufacturers are very averse to handing out any information about the actual relative rolling resistance of their tires. Some folks have gone so far as writing the manufacturers with no joy.

There was a Green publication that did some research/testing but it's out of date, so I don't know of any reliable way to find out the RR of any given tire.

 

Goodyear Integrity

Unfortunately, our Prii come with poor tires like the Goodyear Integrity. Read the review here.
http://www.tirerack.com/tires/tires.jsp?ti...romCompare1=yes

Especially read the "reviews" from owners of various models from Ford and Toyota. The major complaint seems to be with hydroplanning. Drive slowly in rain, people.

For more on tires of LRR, you may try this good article.
http://www.hybridcars.com/tires.html

It says that Toyota no longer use LRR tires due to customers' complaint.

 

Thank you Ceric,

Good info on tires and driving, especially specific tires to look for.

Rick