45,000 is about my borderline replacement point.

Your issue is generally tire related. Any cupping on the tire surface can cause vibration and it doesn't take much for tires to start cupping. Some brands are more susceptible than others due to rubber compositions. From my experience, the cupping is a result of tire balance as primary. However, worn suspension bushing will contribute.

Find an alignment shop and have them do a balance/alignment. In general, I have had good experiences with Discount Tire.

If you were in San Diego area I have a trusted shop for tire and alignment work.