all of you with air gauges

i have a dual needle gauge, that i am going to put in my truck, i am molding it to the AC vent trim peice, above my radio, on my 96 sonoma. what size air line does everyone run to their gauges when you put them in the dash? i dont want to run 1/2 or 3/8 line because of the size, i have some 1/4 inch line that would be about the size i need to run up through my dash. but i dont know if 1/4 would be too small or not to function right. i need info, thanks in advance