what did you end up doing? I recently bought tires online in Switzerland and there were more choices for a the 17inch - i went with a new set of Goodyear Asymmetrical 6s (215.45.17 and 245.40.17) . I checked https://www.reifendirekt.ch/ and looks like you can get both Primacy 4 or Pilot Sport 4s in the 16inch sizes.