My 2011 Mazda3 with the 2.5 6 speed is having weird vibrations in the front at 70 mph. I had the tires balanced but maybe I through a weight? The rear bearings are bad for sure so Im wondering if the fronts are bad already too? Has 103k miles. Seems early to me for front bearings to go out but Im use to my Toyota ones that went 250k before changing them. Can we buy steering knuckles with new bearings already installed for an easy swap?