Originally Posted by Vic55
I like form and function---- 21 inch wheels weigh alot---- my 20 inch HRE's weigh 21 lbs and you will notice 7 to 8 lbs per corner in the increase unsprung weight. Couple that with increase rotation mass/inertia and performance drops.
But it all depends on your needs and how you drive. I like to drive my cars fast and never want the performance to suffer. I have tested 21 inch wheels on my CLS63TT with HRE and I could clearly tell the difference from a dig and roll with the 21's on vs the 20's and that was with HRE's which are lighter. But thats me. YMMV.
That all being said, what about those that chose the 20" OEM option over the 19"? It seems that 20" is acceptable on the F10 - but I believe its because it's a factory offered option. If it were 19's only from the factory, I bet everyone would be saying the same thing about aftermarket 20's - just like everyone did on the E60 M5 (I had 20" HRE's and could not tell the difference in performance at all as compared to the stock 19's).
just some food for thought....