Tires Bias or Radial?

Can anyone feedback on their sense of yea's or nay's on either of these. I do know you can mix them w/o much issue for street use and BMW sold a bunch of bikes fitted that way. I'm inquiring with track days in mind not the commute to them. Check out this beauty. Here's a neat place to scan what's out there, but tag the tire by size to do so.
http://www.cheapcycleparts.com/tires?gc ... 7QodNXz2Jw

130/65x18 AM23 $228.99


Old cracked one fits on Peel. '77 Suzuki GT750 Water Buffalo hub.