My Sienna is now 1.5 years old - we just replaced the tires on it. Word of caution on the run flat tires -- they, in a word, suck. Gas mileage isn't as good with them, and pretty much every tire place we talked to told us not to waste our money on them (they are expensive) when we were replacing them. We had to purchase 5 tires and one rim as there is no spare in the vehicle, and need to have the dealer build the spare holder under the vehicle to carry it.
That's the only downside to the vehicle. Other than that, I love it.