PCD = pitch circle diameter, i.e. the diameter of the circle drawn through the centres of the mounting holes. Most oldies would quote this as 4.5", but the modern metric generation like to say 114.3mm. This measurement also holds true for the Z31 and Z32 5-stud wheels. On a 7" wheel zero offset is about the right fit for a 240Z/260Z/280ZX, offset being the position of the inner mounting face relative to the imaginary centre line of a sectioned wheel. Most Wolfrace are a fraction off zero - this information will be cast on the rim of the wheel (hence previous comment to see if this varies and also to identify which "generation" of Wolfrace you have. My guess is that there are pre-GKN, GKN and post-GKN variants. The anally retentive should step forward and identify themselves). Another way of assessing wheel suitability for an application would be "back-spacing" - easier to understand, it is the distance from a straight-edge laid across the rear rim to the inner mounting face, e.g on a 7" wheel with zero offset, you would expect this to be 3.5" + the thickness of the rim bead. The wheel width and wheel diameter quoted relate to the tyre mounting face, not to the overall dimensions of the wheel rim lips. You may see the letter "J" associated with wheel sizes - the "J" refers to the profile of the wheel lip, e.g. 7J x 14.