Racecarl, to measure wheel bolt pattern, draw a circle which passes through each bolt's center, and measure it's diameter. Then count the bolts. The first number is the number of bolts, the second is the diameter- 4 on 4.5 is 4 bolts on 4.5" diameter. If the number of bolts is even, just measure from center to opposite center. There is also the issue of the center hub diameter and the offset.
