Something else to think about when using radials on any rim is making sure the sidewall relationship doesn't become so severe that it causes squirming problems. The simplest way is to measure the actual tread width of the tire you want to use and make sure it is plus or minus one half inch of the width of the rim. Most typical passenger car radials have a single or two ply sidewall so an 8 inch treaded tire on a 6 inch rim puts the sidewalls at an angle where they do not properly support the load on the wheel. The old bias ply tires had extremely stiff sidewalls so pretty much anything that would fit on the rim within reason would work.
If your Nova has 6 inch wide wheels then a radial with 5 1/2 to 6 1/2 inch tread width should be ideal.
High performance radials are even more critical for exact rim width. You tire dealer should have a chart with rim recommendations for the tires you want to buy.
