Choosing bias ply or radial tires is a decision that most old car enthusiasts have to make at some point. In this article we will examine the pros and cons so that you can make a decision.
Bias Ply Tires
“Bias ply” refers to the tire’s internal construction. In a bias ply tire, the fabric cords run at a 45-degree angle from one tire edge to another. A type of crisscross pattern is created by laying the cordsduring manufacturing, because during the manufacturing process each subsequent layer is placed at a 45 degree angle to the cord underneath it. After the tire is complete, the 45 degree angle ply construction leads to a narrow tread pattern with a very little sidewall bulge and sharp shoulders.
Image by Antonio Thomás Koenigkam Oliveira
Bias ply tires are firm and theirhandling characteristics are quite different from radials. They do not hug the road quite as well and have sort of a “wandering” feel to them. This wandering is not dangerous, it just feels different to the average driver, particularly at interstate speeds.
Bias ply tires were used on American automobiles until the early 1970s, so if you’re restoring a car from that era or earlier, a bias ply tire is a great choice. Especially if you’reseeking a correct period look.
Radial Tires
The term radial refers to how internal plys run straight from bead to bead. When manufacturers lay down theplys in this “90 degree”fashion, the tire conforms to the road’s surface better. This makes for a better ride, especially on rough roads which would cause bias ply tires to wander a bit.
Radial tires are a popular upgrade for old car owners who like to drive their old car quite frequently and are less concerned about a period look. Radial tires feature tread “siping” to increase wet weather traction whilst discharging water from the tread surface. The folks at Mullahey Chrysler reminded us to consider that a radial tire will have a wider footprint than a bias ply tire of the same size. This increased contact patch offers more stability and more traction, while the rounded shoulder provides extra traction during tough cornering.
It Is Your Decision
Until recently, old car enthusiasts have been faced with the old bias ply versus radial dilemma during restorations and it has been one or the other. Coker Tire, a big manufacturer of tires for classic cars, has come up with a solution to the problem. Their American Classic Bias Look radial tire has 90 degree ply alignment but alsocopies the look of old 45 degree bias ply designs.
In the end, the choice of tire type is a decision that all old car ownershave to make when looking to put a new set of tires on a vehicle. The look of the tire is a personal decision that needs to be weighed vs the handling; so, do you want your tires to have the old “bias ply” look or do you want the drivability of a radial? Usually, people who drive infrequently and go to car shows, tend to choose the old bias ply look. For people who enjoy their cars via frequent use, typically go for radials.
