general problems of the 2007 Toyota Highlander Hybrid

2007 Toyota Highlander Hybrid limited tire issue!!!! I maintain my vehicle very well rotate my tires since I bought it in 2007 new! I have approx. 81000 miles cureently and have just put my (4th) set of tires on this vehicle. The tires don't last the miliage waranty that the dealers place on there tires 60-65 k tires! I was very lucky that I checked my tires and every time found that my tires are going below the tread max allowed (bald) at 19-21k on them only!!! Toyota stated to me on the first set of replacements that they don't waranty tires. . . Okay then who is responsible for the misengineering screw up on the tires to this vehicle. I also spoke with other people about this and found out they have the same issue, and someone somewhere is to blame. I hade a 2004 Dodge dakota quad cab 4x4 for my last vehicle and had 90 k on it and was only on my 2nd set the first set finally wore out at 66k so if that truck can go so many miles then how can an highlander get so little miliage out of the same weight ratio. . . It's obviously a tire size manufacturing issue with the specs being all wrong for this vehicle. One other thing is that Toyota puts the same tires on other Toyota's for that year ( rav 4, seinna, camry,and the standard hylander). Obviously this is an issue from the get go because the hylander hybrid limited is a lot heavier then the other cars mentioned, so how can they have the same type of tire!!! this is a mistake, overlook, and or crime. The american consumer should be aware of this and compensated for this issue, and if this issue was known by the people in charge then legal action should be started !!!! but, an investigation should be open to correct and compensate the consumer of these vehicles that I have and other years that have this issue. . . If you had to buy 4 sets of tires on a car that only has 81,000 miles on it you would complain as well!!! tires are not cheap!!! especially the size for this vehicle a 2007 Toyota Highlander Hybrid limited.