[400TT]

315x35x18 size is certainly a very odd/rare size. You sure you have that right.

Best bang for buck are:

315/35/17 Sumitomo (Tirerack)
335/30/18 Pilot Sports (online Viper dealers, ebay(US) etc)

I have some 335/30/18 Pilot sports here that I bought off Ebay US. Brand new, stickers on the tread....bargain.