Pontiac: Steering Shaft & Wheel Vibration

I've had the intermdediate steering shaft lubed in my '02 Bonneville
at 30000mls. I'd heard about this issue in several other mid and
full-size GM cars, but so far thought that somehow I'd be luckier.
Anyway, I wonder if the lube kit contains a grease that won't dry out.
Would anybody be able to say?

Now, another issue that has been endemic to the H-bodies is a resilent
vibration at a specific speed, between 65 and 70MPH in my case, that
refuses to go away with wheel balancing. After replacing loose tie
rods, the issue was still there, and after road force balancing, the
dealer concluded that the tires were bad and that they'll be replaced
under warranty. So far, so good. But is this the actual fix? Now,
to those who work in the dealer service area, can I get to choose the
tire of my liking, must it be like the original tire or must I accept
whatever they get?

TIA

every tire has a small "V" or a dot stamped on it somewhere. the air
valve stem must be alighned with the "V" or dot on the tire. becuase the
tire is counter balanced for the valve stem. now remove all the wieghts
inside and out and test drive. maybe the tire is on the rim backwards,
inside-out. this is a tire balance problem, generaly it will go away
with a little TLC. could be alighnment but we doubt it. what about
wheel covers switch rotate tires, front/back back/front