If you are replacing an existing baby moon, then the easiest way to determine the correct size is to just take one cap off of the wheel, turn it over and measure the inside diameter of the baby moon hubcap. If you don't have existing baby moons to do this, then use the instructions below.
* Important Note:
Instructions below are for wheels with 3 Nub center cap Hubs.
"But my Hub has 4 Nubs" Click Here
Step # 1: 3 Nubs
Measure from the tip of one of the Nubs on the center cap Hub to an imaginary curved line that represents the outer edge of the Hub ring as if no Nub exists (as shown above in Fig. 1). Then write the measurement down.
Now measure from one of the Nub tips to the outer edge of the Hub ring centered between the other 2 Nubs (as shown below in Fig. 2).
Finally add the measurement from Step 1 to the measurement in Step 2. (Use the chart found below Fig. 2 to help you determine which size Baby Moon (Dog Dish) Hubcap that your wheel requires. These Dog Dish hubcaps only come in one of the 6 sizes shown in the chart below).