High performance tires, road or track, for cars with 15in rims on vintage cars (with suitable aspect ratio) have become really scarce on the market. What's left usually is quite expensive. This holds even more so for 14in rims (with Hoosiers pretty much the only choice). I recently switched from 14" to 15" on my Alfa so that I can run Yokohama Advans. Within a few tire changes I'll have recovered the cost of the rims (Panasports)...