Yes, tow is a Scrabble word!
...and is worth 6 points in Scrabble, and 6 points in Words with Friends
tow
Verb
1. Drag behind
Noun
1. The act of hauling something (as a vehicle) by means of a hitch or rope
What Scrabble words can I make with the letters in tow?
3 Letter Words
2 Letter Words