If you own an old collector car, you have probably thought about this: Do you want your tires to have the old "bias ply" look or do you want the modern handling of a radial?  In this article we will look at the pros and cons.

Bias Ply Tires - In a bias ply tire, the fabric cords run at a 45-degree angle from one edge of the tire to the other.  As the cords are laid on during manufacturing, the next layer is placed at a 45 degree angle to the one resulting in a crisscross pattern. When finished, the 45 degree angle ply construction leads to a tall tread pattern with sharp shoulders and very little sidewall bulge. 

Bias ply tires handle quite differently than today's radials do. They ride "firm" and many report that they have a sort of "wandering" feel to them that requires a constant hand on the steering wheel. Bias ply tires were used on American automobiles until the early 1970s, so if you are restoring a car from that era or earlier, a bias ply tire is a good choice.

Radial Tires - The term radial refers to fact that the internal plys run directly from bead to bead (no crisscross pattern). Radials have a more pleasant ride, especially on rougher roads. The folks at East Hills Jeep reminded us to keep in mind that a radial tire will have a wider footprint than the equivalent size bias ply tire. Radial tires also feature "siping" in the tread, which helps discharge water from the tread surface and increases wet weather traction.
Radial tires are a popular upgrade for old car enthusiasts who like to drive their old car constantly and are less concerned about the "correct period look."

A little of Both

Until now, classic car enthusiasts have been faced with the bias ply versus radial decision during restorations. Coker Tire, a major manufacturer of tires for classic cars, has come up with a solution..  They have a special tire called their "American Classic Bias Look Radial Tire" has real 90 degree ply alignment but in a way that mimics the look of old 45 degree bias ply designs. Check out their website for more information.