Tow Rope?

I'd go with a tow strap. There are three tow straps on the linked page. They are from Harbor freight and not the highest quality but should suffice for the occasional tow.

http://www.harborfreight.com/catalogsearch/result?keyword=tow+strap

EDIT: I would personally go with the 3" $29.99 strap. It has 9,000lb working strength, 27,000lb break strength.

Have used chains for decades and when we did it right a pipe with a chain inside so it pushed and pulled. And still use chains for equipment. Got a 30,000 lb tow strap these days.

But these synthetic ropes are AMAZING, 5/16 rated 15-20,000 lb and 10 more to break and no whiplash. They are expensive, wear easy and suck up dirt.

I work on the design of custom lifting equipment professionally, and wanted to answer your questions on breaking and rated strengths. I will use device in my comments below to mean any pulling device (strap, chain, rope, etc). Breaking strength is the minimum force it would take to break a new device in a straight line pull. Working load is a lower value, and is the maximum tension load this device can be rated to carry. This value is typically lower, usually by a factor of 3 to 5, but sometimes even more than that. The exact safety factor depends on the type of item (strap, chain, etc), the application (vertical lifting often requires a higher safety factor and proof testing) and the relevant industrial standards. You NEVER want to load a pulling device in excess of the working load value. That safety factor is the margin to help account for all of the unknowns in your pull or lift. A tractor mired in mud can require a pull of much more than the weight of the rig. Any damage to the device can reduce the capacity. Shocks and other unknown and/or unplanned occurrences during use can also take up some of the safety factor. Always use the RATED capacity of a device when planning a pull or lift. Anything else is just asking for trouble.

Sorry Lilys Dad.. I assumed it was for pulling a truck out the ditch with another truck set up.. Using a winch you do not want the true kenetic energy type line.. You will wear it out fast on a winch and it was actually not designed for that use. There are soft winch lines out there for your particular use.. I would hate to see yall spend money on something you will be using not in the way it was intended and wear it out fast.

If you are using a capstan winch, they are typically designed for rope, not straps or chains. You also want to make sure that the rope fits the specs of what the capstan is designed to handle. I'd suggest checking with the manufacturer of the winch and seeing what materials and sizes they specify. Remember that with rope, the first knot you put in it reduces the capacity of it by around 50%. Pre-made ropes with braided end connections are rated with the end fittings accounted for.