Can you use it as a measure of inflation? No more than you can claim that the new 8.5 oz cans of soda are a measure of inflation. But they are.
When the same dollar buys a lower quantity or quality of merchandise than it did last year, that effectively is inflation. Difficult to measure, but easily visible to the consumer all the same.
That has been my assessment as well. Higher milage tires might or might not be available for a particular vehicle. There are tire manufactures that claim ~90K tread life. Those tires have close to twice as much tread as your standard all season tire and have lower speed ratings. If you want that kind of tire, you have to find out if it is available before you buy the car. Your not going to find that kind of tire being available for sports cars or higher end sedans...