If you can't find a mat like the one at Tractor Supply, check for tractor trailer mudflaps. They aren't real long but they have the same overall benefit. I've trimmed the width down otherwise they tend to be too wide but can work.
One recommendation is to either cut a hole as a handle or put some sort of strap on it. If you get in real sloppy conditions and use one of those sometimes the recover of the mat is very difficult with out it. They get real slick and have a lot of suction for you to overcome.
And if all else fails: [video]http://sfglobe.com/2015/10/21/man-straps-used-wood-to-truck-tire-to-get-out-of-the-mud/?src=fbfan_46800&t=fbad&k=ip2a3g1t1[/video] :smiley_drive: