Gen 2 Sienna owner here, and I am disgruntled over tires. I've owned my minivan since 2017, and I go through a set of Bridgestone Driveguard RFT's once a year. $1K mounted, balanced, and out the door. Every. Stinkin'. Year. They are rated for 60K miles, but I average only 21K per set, which coincidentally, is about what I drive per year.
I keep the air pressure topped-off and I bought the lifetime alignment at Firestone (an excellent investment, I've had close to a dozen in these 5 years). I keep them rotated every 5K miles or so. I've had to shim the rear axle to keep it in the green. The fronts are in the green with no modifications. I've replaced the wheel bearings, struts, and links. Tie Rods and Ball Joints are still good. And yet, the tires wear unevenly. I can't explain it.
The tires wear excessively on the inner edge to the point that the belts show with 4/32" left across the surface. Although the rears are screwed (they're at -1.8° camber with maximum positive shimming), I am considering shifting the front camber. They're at -0.8° camber. I can replace the strut bolts (Toyota #90105-17009 in the upper and #90105-17011 in the lower) to bring the camber to +0.2°, which is still within the acceptable range, but am uneasy about that. Any opinions?