Stretch and squash

What we really need to see is a screenshot of your comp with the modified properties of the layers revealed. Select all critical layers, press UU, PrintScreen and paste and we can help you. If you're on a Mac Cmnd + 3 will capture a screenshot, then just drag it to the forum.

If you want the movement realistic then my approach would be an expression to drive the rotation of the wheel and a displacement map to deform the tire. Something like this: Dropbox - Bouncy Wheel(CC (14)).aep

This is what that comp looks like:

Let me talk about the wheel first. I used a polystar to create the spokes, a stroked ellipse (1) to create the rim, another ellipse (2) with a diameter larger than the first one with dashes and round caps added to make the tread. I wanted the rotation of the spokes to match the rotation of the tire tread so I used the Pickwhip to tie the rotation of the two ellipses together.

To make the roll along the ground I created a fairly simple expression to take the y position of the layer and turn that into ellipse 2's rotation value. The expression looks like this:

s = content("Ellipse 2").content("Stroke 1").strokeWidth / 2;

d = content("Ellipse 2").content("Ellipse Path 1").size[1] + s;

c =  Math.PI * d;

a = c / 360;

p = transform.position[0];

     p / a

Here's what it all means. The "s" variable is simply half the stroke width. "d" is the diameter of the ellipse plus half the stroke width

"c" calculates the circumference of the wheel. "a" calculates the rotation angle based on the circumference. "p" is the Y position. The final step is to divide the position value by the angle. The wheel now rotates perfectly along a horizontal ground line. If you want the wheel to rotate as it follows a curved path at an angle the expression gets a lot more complicated.

Now let's talk about the displacement map. I started by just double-clicking the Rectangle tool to create a shape layer the same size as the comp. The rectangle is filled with a gradient. Displacement map works by moving pixels up or down based on value. 50% gray doesn't move any pixels, white or black moves them one way or the other by the value entered for horizontal or vertical movement in the Displacement Map UI. I set the white as the start color, 50% gray as the end color and moved the endpoint to the bottom of the wheel and put the start point below it about half the thickness of the tire. X values for start and end points were identical to make the line horizontal. I then duplicated the gradient in the timeline and changed the top copy to radial, set the blend mode to overlay and moved the start point up to give me a bump in the road. I duplicated the second gradient again and adjusted the start and end points to create another bump.

The last step is to set the vertical displacement to 100 to squash the wheel and set a couple of position keyframes and added a little movement in Y at the start, middle, and end of each bump.

The effect is fairly realistic. I hope this helps. This project and post are part of a presentation I am preparing for a presentation to educators that teach After Effects.

mattb74522626  wrote I basically want to anchor something to the bottom of the wheel  Thansk so much!!

Like what?   Are you asking how to anchor "something" to the bottom of the wheel or are you asking how to achieve squash and stretch?

It sounds to me like you have some pre-conceived notion of what you need to do and you're asking how to do it.  But do you know your pre-conceived notion is correct and or achievable?

If, on the other hand, you're asking how to achieve squash and stretch re-read byron's post very carefully.  You need  a pre-comp of a wheel turning. You then put that in your main comp and set the squash and stretch using parenting