Unfortunately you are limited in these sizes. The NT05R is the only model I am aware of that is built in the 315/40R-18 size. When it comes to the 315/35R-18 size, the only two tires that are built are the Toyo Proxes TQ (DR) and Kumho V710 (road race).
As SVT_Colin_01 pointed out, the 315/30R-18 size is a little common and there are a few more tires to choose from in this size.
What vehicle are you trying to fit BTW and what are the wheel dimensions (width, offset etc)?