Air line size for towing?

[rhurey]

What's the correct air line size (id) and length to hook between a couple of M939 trucks to flat tow and be able to use the brakes in the towed vehicle?

Perhaps my search foo is bad, but...

 

[fuzzytoaster]

Buy a standard set of the coiled red and blue air lines on semi trucks and 4 glad hands. Works like a charm, I've been using mine for years. Find them on flebay, amazon, etc.

Just the first one I came across..

http://tinyurl.com/klm4l8e​

 

[MtnSnow]

Mine are 1/2" ID coiled DOT air lines made by Parker and are 15 feet long and they are just long enough. I would prefer that they were 20 to be honest (I have the "Heavy" "Tow Bar from ****" so if using a "Medium" duty tow bar which is shorter than my heavy, the 15 foot pre-made coils I bought would be just about right.

 

[Castle Bravo]

3/8"