How will my tire choice affect me?

[latemodel86]

I was wondering what would the car do if I keep a D21 on the RF when the track is slick and black, while I also have a RR D55 on it? What would the car do if I put a D55 on the RF and RR, with the same slick and rubbered up conditions? Stupid question I'm sure, I've never been able to feel a difference except maybe the car losing side bite some, but it's been a while since I've been in a car, so....

Thanks for any help!
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