Toyota Sienna AWD run-flat tires: No worse for wear

Lots of tire life left based on our extended tread-life test. We?ve had a series of blog reports on our Toyota Sienna following the tread life performance of its run-flat tires. (See the links below.) Now, at just over 30,000 miles, (30,247 miles to be exact, as shown) we?re impressed with the wear performance of the tires, which are projected to wear out at no less the 54,000 miles?comparable or better than conventional all-season tires. For those of you just joining us, we purchased a new 2007 Toyota Sienna XLE AWD with the Dunlop SP Sport 4000 Self-Supporting Technology tires (DSST)?run-flat tires. After the road test was completed, we purchased a new set of Dunlop SP Sport 4000 DSST tires for a tread-life evaluation on our Sienna. The evaluation started at the end of March 2007 and now, one year later, the tires still are trucking on. To be fair to the tires, we have been checking inflation pressures religiously; checking alignment, rotating the tires, and measuring the average tread depth in tread grooves (four grooves) across the tire?s tread width and at four places around the tire for a total of sixteen test points. In the course of the 30,000 mile test we measured tread depth of the new tires, and then eleven times throughout the test, most at 2,000-mile intervals. Some readers/subscribers have griped that nobody checks tires as often as we did and most certainly do not check alignments that often. To that end, we checked the tire?s inflation pressure just about every month, just like you should do. As for wheel alignment, we did check it routinely but never had to readjust the wheel alignment settings at all. And then there were our drivers, a sorted bunch of car enthusiasts, office administrators, and maintenance staff who drove the minivan all those miles. Minivans don?t excite many employees here with all the cars that we get to drive at our Auto Test Center, but with the enticement of free fuel, people were fighting over the use of the van, especially for long vacation trips. And so the van has been all over the New England region, and it enjoyed more places than I will ever see, from venturing into the deep-south of the United States to traveling across a wide swath of Canada. At just over 30,000 miles, the tires still have about 25,000 miles or more left based on the fastest wearing groove, before they are worn-out to the tread wear indicator of 2/32? depth. On average, just two tires were about 50 percent worn out, one was just over 40 percent worn out, and a fourth tire had to be replaced after the previous tread measurement point due to an encounter with a large pot hole. The tires were wearing faster at their shoulder grooves with a slight cupped shoulder. That continued to be the case at the last measurement, but the wear progressed more evenly across the width of the tire ensuring many more...