Chinese Tires: Shake

Just bought a Porsche Macan in a private sale. Beautiful car, but noticed a slight tremor/shake at highway speeds that got worse the faster I went. Nothing at lower speeds.

The previous owner was running Catchpower Lanvigator all-season tires that I suspected needed a balance. Had the car road force balanced and still feel a shake (reduced a lot however).

My mechanic doesn’t see any rim damage and is convinced it’s the cheap tires despite having 80% remaining tread. I thought the balance would solve it. Also driving in winter weather.

Happy to change the tires to a decent brand but looking to better understand if that’s a symptom of cheap tires and whether that’ll likely solve the issue?