Bias ply tires! Wow, bet they are hard to get. YES definitely go with radials. The OEM size of 165/80x15 (or 155/80x15 if 4.5" rims) is not all that popular but can be found. Vredestein is popular replica Speedster tire. I actually went with 185/65x15 Bridgestone tires (lowers car maybe 1/2").