Correct Proportioning Valve?

I ran 275/60-15s out back, with a gutted Pvalve,and 7/8 W-cylinders and 10 x 2s . No premature lock up with that. When I fit the 295s on there I went to 15/16.
235/60-14s on the front with both, and KHers.. I'm running less than 52% front weight bias.