There are several things you need to kep in mind, not all tire gauges read the same on the same set of tires tested back to back at the same track one after another I've used three different low pressure Morso gauges that read 3 lbs difference,9.0 to 12.0lbs I ended up buying and using a very expensive accurate low pressure C gauge for my bias tires, I don't loan it out after finding out that there are people at the races that will use a borrowed low pressure tire gauge on there street tires and ruin that gauge, twice I learned that lesson twice , No MAS The other thing to keep in mind is to use only your gauge on your tires and go by the 60 ft. times to find the best pressures for that track that day Another thing about tire pressure is altitude and barometric pressures as well as outside air temps. and tire temps. all affect the tire pressure readings I use to use my fingertips and rub them lightly across the bias ply tire surface to see if the texture was the same all the way across from the outer edge to the inner edge, to low of pressure will make a rough, smooth, rough, smooth and rough again on the inner and outer edges as well as in the center of the tires To much pressure will make the inner and outer edges smooth from no conact and the centers rough Try using 1/2 lb. changes at first and then use 1/4 lb increments to find the pressure on your gauge that your tires work the best at I did find that on my old pump gas Duster(10.0 at 134 MPH in the 1/4) on the original M/T ET Street Radials, 315x60x15 on 10 or 12 inch wide rims that they liked between 18 to 22 lbs, depending on track prep and track altitude. IHTHs