I just installed a new set of these tires on my 98 Olds. Also had it aligned. And what I'm noticing is the same with the old tires. When I get to 75-80 mph I feel ever so slight vibration but the steering wheel isn't shaking at all. My concern is am I wearing out these new tires fast are causing bad tread wear? The car tracks perfectly straight to as the alignment is spot on.
BTW Mark72, your 98 Olds was most likely built on the same chassis as my 99 STS. This car was EXTREMELY sensitive to tire vibrations from "out of round" (it's more than that, but I'm simplifying) tires.
And yes, Road Force Balance did eventually solve my problems. However, I had to educate the tire technician on the Hunter machine, AND had to get the tires down below 15# Road Force (yes, it's measurable) before the tires were right.