Toyota Sienna AWD tires - patience wearing thin

Consumer Reports News: March 06, 2007 05:14 PM

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Owners of the all-wheel drive (AWD) Toyota Sienna often share complaints with us in the recently expanded Cars forums, especially in Tire Talk, the online-subscriber-only tire forum page at ConsumerReports.org. We've also covered the frustration of Sienna owners regarding fast-wearing tires here in the Cars blog: "Toyota extends run-flat tire warranty" and "Toyota Sienna run-flat tires? Spare us."

While most owners were pleased with the overall performance of their AWD Sienna—one of the top-rated models in Consumer Reports tests—few have had good things to say about the standard run-flat tires.

The run-flat tires supplied by Bridgestone and Dunlop provide extended zero-pressure driving for no more than 100 miles and at speeds of no higher than 55 mph--theoretically enough distance to get to a service point to have the tire repaired or replaced. Some owners were unaware of their van being equipped with these tires and were alarmed at not having a spare tire, despite the run-flat capability (Toyota doesn't provide a spare.) Many owners found that the run-flat tires wore out much quicker than expected or unevenly, often within 15,000 to 20,000 miles. Some owners found themselves facing an aggravating annual replacement, costing around $700 or more. Toyota finally addressed the issue last year with an extended warranty on 2004 to some 2006 model-year vehicles, mostly addressing the irregular wear condition. Later-model vehicles came with a revised tire intended to eliminate the fast-wearing condition.

To find out for ourselves, we purchased a new 2007 Toyota Sienna XLE AWD shod with the Dunlop SP Sport 4000 Self-Supporting Technology tires (DSST)--jargon for run-flat tires. You can see a vehicle road test report on this vehicle and the front wheel drive Sienna in the June issue of Consumer Reports and on ConsumerReports.org soon.

We found a nice little Tire Information booklet in our van for the run-flat tires, describing how they work and should be maintained. Interestingly, the booklet states: "Tread life of AWD Sienna's run-flat tires may be as low as 15,000-20,000 miles and may be as high as 40,000 miles."

We're going keep our AWD Sienna for a long-term evaluation to see what we get in terms of wear mileage and if the changes the tire manufacturer made to the tires have helped eliminate its propensity to wear unevenly. We're aiming to run the vehicle to the point of tire replacement and will share with you along the way how the tires are wearing. We hope to start the evaluation in the next couple of weeks.

—Gene Petersen