I use
Labocosmetica NERO - Tire Dressing Gel/
Gray Microfiber Applicator, about once every six months; its somewhat expensive but worth it, I purchased a gallon. For weekly maintenance, I simply use
Armor All Tire Foam and work it in using a detailing hair brush.
During tire rotation, each wheel/tire is washed, brushed, cleaned inside and out, air dried, followed by applying a coat of the gel above or Tire Foam, as needed, on both sides of the tire'; who does that?

I do and they usually ends up looking like this.
View attachment 30264