18" lower

Rf upper 10"
rf lower 18"

am i missing out by not having the longer 19" plus lower?
Could i get away with adding a 2" spacer or try to find a longer lower?

Didn't know if this could be part of the probelm. Looser, after center of turn getting back in gas in feature, on the really short dry slick tracks.

I think it's more the relationship between the two and how long your particular upper is (a wheel spacer is not going to change that). My car takes a 19 1/4" lower but only an 8 1/2" upper. I would have to think you're losing a good deal of camber on the RF through roll/suspension compression (meaning the camber curve is not good with those lengths).

What kind of car do you have?