This topic seems to pop up from time to time. The suspension and steering on any car built before radials were common aren't "tuned" to handle radial tires. Adding a set to your Kaiser will improve straight line handling since the tire won't try to follow grooves in the road like a bias ply tire will, but that's about where the advantage ends. As was mentioned, slow speed steering will be more difficult and it's been said that radial tire geometry puts undue pressure on rims not designed to handle the stress. I had a set of Michelin radials on my 53 and once I switched back to Firestone bias ply tires, it was as if I was driving a different car - for the better.
The problem we have today is that a bias ply tire can cost twice what a similar sized radial does - which is one reason folks look to make the switch. There are companies that market radials supposedly designed for older cars. One of them is mentioned below, however, their product doesn't come cheap.
Bottom line, if cost is a factor, then radials will not break the budget. But, your drivability will suffer. If you want the original look and feel, then spend the extra few bucks and go with original equipment.
