Does anyone know why the 2005+ mustangs use tires that are less wide and have a larger sidewall? Why does 94-04 use 315/30/18 on an 18 x 10 rim and an 05+ uses 285/40/18?

 

Just has to do with them being totally different cars with different OEM tires, etc. You may be able to squeeze wider than a 285 on an 05+. I have no idea, but as for the 94-04 cars a 315/35/17 is the same overall diameter as the stock 245/45/17.

You have to make them as close as you can or your mileage and speedo will be off. Maybe the 285/40 tire works out to the same as the stock size on the 05+

 

i know the diameter is the same, it's just that i was wondering why you can't put a wider tire on a 10 inch rim?

 

Who says you cant?

The tire will fit on the rim but it may rub on the car when its on there.

I have 315s on my 10.5" wide wheels so a 305 or 295 should fit on a 10"

 

ok thanks for all the input everyone but I am not asking about the width of the tires, i am curious why the sidewall is so big. my stock tire is a 235/55/17 and according to the tire sizes thread a 17 x 9 for my car needs 265/50/17. 50? i want some damn low profile tires.