Antique Tires Part 1: The history of Bias Ply

TIRE GUYLet us go back in time, back when fuel prices were in cents per gallon rather than dollars. Back when the cars ran on what we now call "antique tires".

For sixty years, bias ply tires ruled the roads all around the world. Today there is still a niche demand for bias ply among car enthusiasts and collectors of cars from a bygone era. The radials of today handle differently to bias ply and many vehicle owners prefer them for a few good reasons.

Concerns about radials

The first reason simply being authenticity. Many restorers want the vehicle that they have painstakingly restored, sometimes over decades, to be exactly as it would have looked and driven the day it came off the showroom floor. That means everything has to be original from the seats, to the suspension and even the tires.

 It makes a lot of sense to me. Step into a car from another era and it is like sitting in a time machine.

The next reason is simple preference. Some prefer the way their car runs on bias ply. A good example of this is in farm tractors, where many like to stay with bias ply.

The third reason is a good one. Although one which can sometimes suffer from the influence of myth rather than science. For cars designed to run on bias plies, it is possible to cause a problem by running radials.

The first thing most enthusiasts do is to "beef up" things like suspension and steering to handle today's road conditions. However, if that hasn't been done: if a collector's car runs its original suspension, it is feasible that suspension designed for bias ply tires will find radials unfavorable or even harmful.

Some tire history

In 1898, the process of vulcanizing rubber was discovered. To strengthen and form the rubber, layers of fabric cords were embedded into it. Each layer was an alternating diagonal on the bias of the bead cord.

Cotton cord belts, then rayon and nylon cords. In 1959, steel-corded tires were introduced, then fiberglass in 1963. Bias-plys started to disappear in 1965 when radial tires emerged in the showrooms and grew into the norm. 

Vehicles produced prior to 1965 were generally equipped with bias-ply tires. Radial tires became the standard by 1973, mostly because of the better fuel-economy achieved with radials.

The great advantage of bias-ply is the extra load-carrying capabilities. Bias-ply can carry more than a radial, but at the price of faster wear. The tread contact area is also smaller on bias-plys, so cornering capabilities are inferior to radials.

Despite the negatives of bias ply, these tires still have a place in the hearts of modern enthusiasts and collectors. There are some very reputable distributors of antique tires and they are listed in part II of this article, which also talks about whitewall and redline tires.

The internet is becoming a huge think-tank for car enthusiasts these days. It is easier to research what you need online, rather than try to rely on some tire clerk, who is just doing the job until they find something else, for information.


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