I believe 15's were an option for those. My 51 has radials because it has newer wheels and I had the tires on an S10 Blazer we were scrapping. I have that combination of 700's on my 66 P100 Step Van, handles and rides good. I ran dozens of that combo on pickups in the 70's and 80's, back when recaps were cheap and available. If and when I get rims for the 51 I plan to get either 15's or 16's in the bias ply. The only thing I've noticed with the van is the tendancy to follow , stay in low spots in the pavement more than radials. There are several areas around here that have a "wheel rut" in the pavement. John
