I recently had my two front tires changed now my steering wheel shakes when i go over 50mph it's not the balance or the tracking.?

Have you used "fix a flat" ? if yes, You have 2-lbs of water inside your tire now. it cost me 70 bucks to find out and this stuff easts chrom weels. Go to alignment shop and tell them to jack up ur car and they use a special machine to turn the back wheels one by one to find out which one is out of ballance ( dont let them take the wheels off and ballance them since they balance tires and speed lower than 50mph and usually stuff happens around 55 to 60mph. for front tires u can just jack up one wheel at a time and put the car in drive and accelerate one wheel is on the ground and the one you jacked up turns and u ask some one to look at the wheel see if it shakes ( it shakes really bad if water inside the tire) do the same of other front wheel. But for back wheels u need that special machine which alignment shops have and all these machines do they turn the wheel up to 130 mph to see if it shakes or not.