I am using 740 steel aftermarket wheels with my snow tires on my '99 v70. Everything appears to fit OK except that I can not get them to balance on the front. I have tried several combinations with these wheels and the Blizak tires with balancing at 2 different shops , nothing seems to work. The imbalance appears at about 65 MPH and up. Does any one have a clue as to what may be wrong here? Wheel balance is not rocket science.

Sim suggests that there may be something wrong with one or both of your front tire/wheels. For a quick test, move them to the back. If this doesn't help you may be able to have them spun up and balanced on the car.

If you have had these re-balanced twice and still get the same vibrations at the same speeds, you may have something wrong with the wheels or the tires that normal balancing won't correct. Your tire/wheel assemblies may be perfectly balanced, but there could be some runout in the wheel or a problem with the tire that results in this vibration when the tire is loaded and running on the car.
Hunter Engineering makes a machine that can easily detect these problems, if they exist. It measures the runout of the wheels and the runout of the tire while it is under load. Go to this website for some detailed info:

www.gsp9700.com

They also tell you what tire stores in your area have this machine. Price to have your wheels/tires checked runout matched is between $15 - $25 depending on the shop. Pick the shop that you have confidence in their knowledge of how to use this machine. I have personally had vibration problems corrected with this machice on my cars that re-balancing would not solve . Good Luck.