Normal
I was irratated with my 23R as it had noticably more road noise (not exhaust noise road noise) than my 21/37", figured ford found another way to cheapen them up, finally after a couple weeks I remebered I had put husky wheel well liners on the 21. I didn't think the difference would be that noticiable but it was night and day every time I drove it and I kept my 21 so every once in a while I would still drive them both on the same day etc.....it went away with liners added to the 23