If you need to select a circle, whether perfectly round or not, here is an easy way to select it the first time.
We will select the front tire of this car.
First be sure the rulers are showing by using ctrl->R
Next select the move tool and left click in the ruler area on the left and drag a gridline to the left edge of the rim, then repeat for the right edge.
Now do the same thing using the top ruler, and drag to the top of the rim and then another to the bottom of the rim. It should look something like this: The arrows show the ruler area to click in.
Now select the eliptical marquee tool and place the crosshairs at the top left intersection of the gridlines, left click, hold, and drag it to the bottom right intersection, then release.
Your circle is now selected and you can do whatever you need to with it, Color it with hue/saturation, Cut it out. Whatever.
See, I said it was easy!
Linear Mode
