Re: My Sienna Eats Tires??
I think the OP should get some tires with a treadwear warranty. Yes they are pro-rated, but if you're really getting 1/2 the life out of them, and taking the van in for regular rotations at the same shop, then a replacement set should cost you half, once the treadwear warranty is applied.
Keep your reciept and tire warranty information, as well as the ones from whenever the tires were rotated. And anything else the tire shop says you need to ba able to sucessfully claim your treadwear warranty.