23mm front 25mm rear ???

fennerjames

I have Zipp 404 's on my Boardman.I have decided to put 23mm tyres front and 25 my rear. I tried to see what if any the benefits are for a 80kg rider,I can't really make sense of it all,so simply is this the best combination for a 70.3 IM ?,if not what is and  what are the best tyre pressures in dry conditions,remember simply !