omegavx:
.
not sure what your primary goal is with the wheel/tire switch ......
.
but you may be downgrading a tad in the handling/cornering area by switching to a 16" 75 (series) tire ......... compared to the OEM 245-60-18 .. and especially if you are running a 255-55-18 ..
.
if this is a concern - and it may not be - some of the others on this site can give you an idea on the differences between the 16's and the 18's on a VX .......