base front: tubular 0.94inch/24mm diameter - rear: same as front
(FE7) front: solid 1.18inch/30mm diameter - rear: tubular 0.94inch/24mm
ZR1 front: tubular 1.02inch/ 26mm diameter - rear: solid bar 1.02inch/26mm
info above taken from COR-VETTE SPECS by Mike Antonick for '95 models
Z07/Z51 weren't stated as available options
Measurement for diameter can be taken with Dial or Digital calipers or by measuring circumference [by wrapping a string around bar (measure length)]take that value and divide by 3.14. Circumference divided by pi equals diameter.