I have noted what to me, seems like a significant drop in my highway mileage (I mainly drive highway) since installing new tires a little over 1000 miles ago. Is this common? Went from the stock Cooper Zeon RS3-As on my 2013 Focus that had ~48.5K on them to General G-Max AS-03s. I realize that the General's have a bit more aggressive tread pattern but I wouldn't think it would make that much of a difference. I see it as a consistent 3 mpg drop since getting them.