We will need measurements A, B, and C for any panels that are not horizontal. Measurement A should be straight across (not along the bottom angle). For B and C you should hook your tape measure to the bottom of the panel and measure up to the top of the door at the front and rear edges of the panel.
On the wheel well panels measure from the straight edge to the top of the rounded corner as shown below.
If you have a rear door as shown below we will need measurements A-GDownload larger version here
If there are any other panels you are not sure how to measure just send us a photo and we would be happy to help.