Question on cable selection for Vandersteen 1

I have a tube amp coupled to a pair of Vandersteen Model 1 speakers coupled to 15/35 watt tube amplifier. They sound pretty good, but I am using really cheap speaker wire. I am wondering which is the better choice: 14 mm or 16 mm cables with banana plugs? Will the 16 mm cable give me too much base or is the higher diameter the better one in general? I play mostly rock.