I use my hand and feel the slicks from the inside to the outside and use the air pressor to get a uniform feel on the slicks, radial or bias ply.
On the bias ply slicks if you feel the outer and inner edges and they are rough and same roughness in the middle that tire needs more air in them to get the same feel, texture all the way across.
If most of the tire is rough but the edges are smooth let some air out, I use 1/2 Lb. increments to get me in the ballpark and fine tune from their in 1/4 lb. increments, I try and use as much pressure in them that I can as long as they don't spin IHTHs