Out of curiosity, why'd you choose p18's and px 12's but not include fks 155 or fks 120's? Also, if you'd prefer a 18 din why'd you pick the px 12's over the px 18s?
As a rule of thumb try to pick a binding where your din will be in the middle of the range and optimaly ±2 from the max/min. So px12's are a 3-12 din range so an optimal din would 7.5 and a range of 5-10. P18's are an 8-18 din so an optimal din would be a 13 and range of 10-16 and so on...