Metal air line sizing

[bones1]

Anyone know off hand what size tubing the air lines are in the frame rail under the drivers side?. I have one leaking, rubbed through there. Feels like it is about 1/2 tubing but not sure. Also should I, would you , replace the whole line or is it OK to use a compression fitting on the air tubing?.
Thanks.

 

[m-35tom]

most of the line is 3/8", but there is some 1/2" . replace it with truck air brake line. if you just want to patch it, it is copper and compression fittings are fine since the pressure is low.

tom

 

[bones1]

Thanks Tom. I will probably use copper as I have it lying around.

 

[Autocar]

Make sure you use DOT certified air brake fittings. They are different than hardware store fittings. Available at heavy duty truck supply houses like Fleetpride. Usually made by Bendix-Westinghouse. Keeps truck legal.