Had appointment to get my tires that I already own installed. My car manufacturer recommends 225r50. I have been running R45 tires for two years and they work fine... just a tiny but smaller around (so slightly lowers the car). The R45 tires Ive been driving on were sold and installed on this car professionally before. Desk guy said they wouldnt install my tires because not r50. Hes wrong: if all same diameter then its perfectly safe. The guy has zero education... spreading misinformation.