Vibration is bad between 50-60mph

[surfer808]

I just lifted my truck 5" Tuff Country and put on 33" MTZ tires. I have heard various opinions on alignment. My friend from Goodyear told me that I don't have to re-align my truck after putting the new tires on. I aligned it after the lift was done but not after the new tires were installed. Then, the guys who did my lift and tire installation recommended that I do align my truck after tire installation. I didn't re-align the truck yet after tire installation but I do recognize a lot of vibrations when I reach around 50-60mph. The steering wheel is straight but the vibration are irritating. Who can help me out with this issue? Advice please!!