What size?

[jmag86]

And what is a good cut off pressure for a 86 1\2 ton with a 5 gallon tank?

[bludshaker]

I run a fixed pressure switch. It kicks on @ 165psi and turns off @ 200psi. I would run a 200 psi switch or something close to that. But like N2TRUX said you don't want to get a pressure switch thats greater than what your compressors are rated for. I am not familiar with the compressors you mentioned but I'm sure the manufacturer could tell you what switch to use. You need a 200 psi compressor to use a 200 psi switch, etc... Hope this helps. (also get a gauge to help monitor your system and you'll always know what your tanks psi is @.)