The difference between the construction of radials and bias is the direction of how these layers or plies are applied in relation to each other and to the center line of the tread. The plies on a bias-ply tire run approximately 45 degrees to the center line of the tread, alternating in direction with each layer. The plies on a radial tire run 90 degrees to the center line of the tire and basically overlap instead of crisscrossing.
The other physical difference between the two is radials tend to be a lower profile tire while bias tire are usually taller and thinner. But both styles are considered to be a safe driving tire for your car, although most would agree that the radials have the better technology and are the better design for higher speed driving.
Having said that, most cars built prior to the 1970’s were designed and used the higher profile bias-ply tires, not radials. Could you have poor handling and suspension issues with radials on your older car…absolutely. If you do, we suggest you stick the cars original tire design and manufacture.
The other thing to consider is how the car looks and shows. Sometimes radials tire can be a big distraction on the look of a collector car, and if you take your classic to Concours events, period correct tires are a must. But we know owners who use a set of standard tires for the car during judging events and then change back to radials for cruising. It’s just a personal preference.
Tires are one of the most important contributors to safety, performance, and handling of your car. Be sure to use a reputable tire company to give you appropriate options for your particular make and model, then you decide what's best for your ride. We suggest companies like Coker or Universal Vintage Tire who specialize in original and retro-styled tires. They even offer the convenience of modern radial tires with the classic look of bias-ply.