Bias Ply Or Radial – what’s best for your classic car?

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It’s a decision that a vast majority of classic car enthusiasts face at some point. Do you want your tires to have the old “bias ply” look or do you want the comfort and handling of a radial? In this article we will look at the pros and cons to help you decide which way is best for you.

Bias Ply Tires

The term “bias ply” refers to geometry of the cords inside the tire. 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 underneath it 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 differently than today’s radials do. They ride “firm” and don’t hug the road quite as well. Many report that they have sort of a “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 an appropriate choice if you are looking for an authentic look.

Radial Tires

The term radial refers to fact that the internal plys run directly from bead to bead (no crisscross pattern). When the plys are laid down in this “90 degree” fashion, the tire conforms to the road surface better. This makes for a more pleasant ride, especially on rougher roads.

The folks at East Hills Jeep in Greenvale, NY reminded us to keep in mind that a radial tire will have a wider footprint than the equivalent size bias ply tire. This increased footprint offers more traction and more stability, while the rounded shoulder provides additional traction during hard cornering. Radial tires also feature tread “siping”, 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 Compromise

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, though. 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.

In the end, the selection of tire type is a decision that every old car owner needs to make when looking to put a new set of tires on their car. The look of the tire is a personal decision that needs to be weighed vs the handling.

  

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