My guess is the wheel alignment.

I notice that whenever I drive about/above 60mph-65mph, the steering wheel will vibrate a bit, not sever, if 1-10(sever) i will rate it ard 4.

Btw, I have aftermarket wheel and goodyear triplethread tire. I got the TL 2nd hand so I have no idea whether the ex-owner did the alignment or balancing after he changed the wheels.

Visual inspection on the tire, I subjectively see that the outer thread worn faster than the middle one.

That's all the information I have.

Any hints or suggestion? Thanks a lot.