Tires Q&A: Tire rolling resistance

In our ongoing series of Q&A blog columns, we will highlight common and interesting questions posted to our Car forums, with answers from our automotive experts.

Question: I bought four Yokohama Avid TRZ tires just two weeks before the 11/09 Consumer Reports issue arrived. I'd read reviews on the internet but none addressed mileage. As I drive an ‘04 Prius, mileage is very important. I had been trying to figure how new tires would drop my mileage a very noticeable 10 percent (from 53.3 to 48). Had I only known the tire ratings were coming I would gladly have waited and would definitely have different tires today.

Answer: I’m sorry the report did not reach you in time of your tire purchase. Until the State of California or the federal government comes out with rolling resistance regulations and ratings, your only sources for rolling resistance information on tires are from manufacturers’ claims and Consumer Reports. Our testing is comparative among the models tested.

Yes, you could have purchased a more fuel-efficient tire, but the Yokohama Avid TRZ is average among all season replacement tires for rolling resistance. Some were better--such as the top-rated Michelin HydroEdge, and the Toyo Versado LX. One point to consider when replacing tires: As tires wear out, you’ll likely see improved fuel economy since the tires will have less rolling resistance as the tread (mass) is removed from the tire. Installing new tires, identical in brand and model as those removed, and you likely see a reduction in your fuel economy. The new TRZ tires should become more fuel efficient as the tires wear. Also, keep the tires properly inflated and check them monthly to get the optimum fuel efficiency.

To see full details on the tire models we tested, check out our Ratings and recommendations (available to subscribers). In addition to our updated Ratings, all site visitors can access our free buying advice for tips on getting started, types of tires we test, features that are important in making a tire purchase, and general tire care. Also, be sure to check out our TireTalk forum to interact with our tire engineers and other drivers.

—Gene Petersen