Going to 15" wheels won't lower the effective ratio because the rolling diameter won't change(15"/60series-v-16"/50series).
The rotational mass may be less so acceleration and breaking may improve slightly. Now if you used a 15"/50series combo that might pick things up a notch!
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Andy V.
99 SE Sport
KKM,No Res,Duals
Semper Fidelis
