My steering wheel starts to vibrate at 60-65mph, and then it gets better when I go over 70mph.

A simple tire balance? Or is there more to it since the vibration lessens at 70mph?

I had a Toyota that did that. I did all the normal things like alignment, balancing, etc. The problem was never resolved, so I sold the car.

That is the usual speed for tire balance problems.

Get the tires balanced before you think its anything serious

Is it front wheel drive? If so, you probably want to have your CV joints / axles examined.

My steering wheel starts to vibrate at 60-65mph, and then it gets better when I go over 70mph.

A simple tire balance? Or is there more to it since the vibration lessens at 70mph?