i have a 05 m6 coupe can my old winter tires 205/50/17 fit on my coupe with steels ?
thanks

 

No. Diameter is way too small. Stock diameter is over an inch larger on the front, and 1.6" in the rear. You will really throw off the VDC system if you do that. That is, if you can even fit those wheels over your brakes. Many steel wheels just don't have the right offsets to fit over large diameter rotors and brakes.

 

I rolled around on 225/50/17 & 235/50/17 on 17x8s. 205 is way to small for the car.

 

are you sure ? coz my stock 330i came with 225/45/17 245/40/17 same as g35 excepts g35 came in 19" but i just check the spec g35 has smaller brake disk compare to bmw tho, 12.6/12.1 bmw has 12.7/12.5

 

What's important here is to maintain the stock overall diameter (wheel + both tirewalls) otherwise the VDC system acts unpredictably and your speedometer will be off.

BMW 330i:
225/45-17 has an overall diameter of 25"
245/40-17 has an overall diameter of 24.7"

205/50-17 has an overall diameter of 25.1"

G35:
225/40-19 has an overall diameter of 26.1"
245/40-19 has an overall diameter of 26.7"

Your size would be off by at least an inch on the front, and 1.6" on the rear. Your speedo would read too high, and the VDC system would think the rears were spinning all the time and activate prematurely.

Also, while the brake disc may be smaller, the wheels have to have the right offset to fit over the brakes. What size is the wheel and what is the offset?

BTW - Here is a tire size calculator to show you the difference in the tires above:
http://www.miata.net/garage/tirecalc.html