Chack out
this site for a nifty tire size comparison calculator. One of the accepted sizes (similar to the standard 800-14) using the curent format is 225/75R14. Working back from that, 205/75R15 or 225/70R15 would be about the same height. I think the optional 850-14's were a bit taller, closer to 235/75R14 so maybe a 215/75R15 or 235/70R15.