I just bought some 17x7 inch wheels with offset +42, hub bore 73.1 and 225/50/17 tires. I get shaking when im riding below 35mi but it smooths out a little when I get to 40mi and above 55mi it shakes again but it smooths out at 65mi. I had the tires balanced, is it possible that they are not balanced correctly or could it be the hub bore is too big because my oem hub bore is 64.1.

 

If I recall our Wheels are Lug Centric not Hub Centric so Hub diameter should not be an Issue...

 

Our wheels are Hub centric. If the hub bore is larger try getting the hub centric rings and see if it clears it up. Also have you tried putting the rear tires up front and see if it continues?