Hmmm


One thing to keep in mind:

A z-rated tire is not just rated for speed. The overall construction will be different than an H-rated tire. I know, and you know that a tire... say 195/60HR15 is supposed to be the same size as a 195/60ZR15. Guess what?!? They are not! The H rated tire will be slightly taller, narrower, and possess a softer sidewall. Z rated tires will have the performance stance and correctly built sidewall for this car! Funny thing- I see people buy cheaper S-rated tires to save money- only to have severe edge wear that requires newer tires sooner! Why?


The softer sidewall on tires as you go down in speed ratings allows the tire to 'roll'. This rolling causes more of the edge of the tire to contact the pavement in corners, thus wearing the edges of the tires. (kind of like under-inflation does!) Higher speed-rated tires have a much stronger sidewall- keeping this rolling to a minimum. Cars are designed with a specific tire type in mind- This is why your tire information label requires a certain size AND speed rating.


Now- would you want to sacrifice your ride/handling/tire-life just to save a few bucks now?

PS:
Your dealer should not have made that suggestion. It opens them to liability- plus it is paramount to suggesting you use 'Auto-zone' parts to repair your CF in the future to save a few dollars, since you don't drive it fast anyway....