Advertisement

Guides

Bias-Ply Or Radial?

  •  - 0
  • The first tires were metal bands. Then came hard rubber tires like those on this 1909 Economy Model G High-Wheeler. - 1
  • This Hudson from the Teens wears BFGoodrich 32x4 4-ply (6-ply rated) BFGoodrich Silvertown cords. - 2
  • The Goodyear Collector Series Deluxe All-Weather tires on Ralph Cornell’s 1936 Olds convertible were an industry standard of quality when new. - 3
  • A GTO owned by muscle car authority Colin Comer wears G70-14 Firestone Wide Oval Sup-R-Belt redlines. - 4
  • This barn-find Plymouth had only been driven for six years, and still had its original F70-14 Goodyear Polyglas tires mounted. - 5
  • An early type, OEM-style Space Saver spare tire and old Chrysler compressed air canister save room in the trunk. - 6
  •  - 7
  •  - 8
  • BFGoodrich Silvertown radials come in 65-80-series models, in wide white or 3/8-inch redline styles with 13- to 16-inch rim diameters. - 9
  • Coker currently offers four sizes of tubeless Firestone Dragster tires that are built in new molds from original Firestone drawings. - 10
  • According to Diamond Back, the company uses a special formula to apply its non-yellowing whitewalls. - 11
  • Diamond Back’s Bill Chapman says he sells only radial tires, but he can supply them in redline or “gangster” whitewall styles. - 12
  • Diamond Back redline tires are seen here on a Pontiac GTO - 13
  • Print

provided by

Source

by John Gunnell  More from Author

How to choose the right tires for your classic.

Photos by the author and courtesy of the manufacturers.


We all know and use tires, but may not be as familiar with their long and colorful history. The first tires were metal bands on wood-spoke wheels. Hard rubber tires came along in 1846, after Charles Goodyear discovered how to vulcanize rubber. John Boyd Dunlop invented the pneumatic tire in 1888, and an Englishman named Palmer developed the single-cord tire in 1900. Bias-ply tires came next, and were the industry standard for many years.

In 1946, Michelin patented a design for the radial tire. John Kelsey, of Kelsey Tires, says the radial was developed in conjunction with Citroen for its front-wheel-drive cars. The Michelin “X” radial went on sale in 1949. “We in the United States refused to go that way,” says Kelsey. “Tire plants here were set up to make bias-ply tires and a huge investment was required to change that, so the switch to radials was done incrementally.” 


History of Bias-ply Tires 1950s-1970s

The brief history of the bias-ply tire from the 1950s through the early 1970s involves the continued evolution of technology throughout the component materials used in the manufacturing of tires. Rayon was eliminated in favor of the stronger, more stress-resistant types of nylon for the body plies of the tire. This remained the ply fabric of choice until the mid-1960s, when polyester was first used. Polyester provided the purchaser of passenger tires the “Rayon Ride” coupled with the strength of nylon, while eliminating nylon’s flat-spotting problem. 

As the 1960s progressed, so did the horsepower race that started in the mid-1950s. Wider-tread footprints were required for the new performance-car platforms, and more aggressive powertrain options that were being developed in ever-larger numbers. Fat 70- and 60-series tires became the standard OEM fitment for almost all of the muscle cars. The development of wide-base tires finally culminated with bias-belted construction. The use of two plies of polyester–combined with two circumferential belts of fiberglass–provided customers with the best in street performance available at the time.

The next step was the radial tire. “What really transformed the market was Sears making a deal with Michelin,” says Bill Chapman of Diamond Back Classic Radials. “Due to volume efficiencies, the Sears radials weren’t that expensive, and they gave 40,000 miles of service at a time when bias-ply tires got about 15,000 miles. Sears sold a gazillion of them. They were put on earlier cars of the day and worked perfect.”


Benefits of Bias-ply Tires

The carcass of a tire is made up of layers of rubber-permeated fabric called plies. The fabric is usually polyester. The plies on a bias tire run approximately 45 degrees to the centerline of the tread, alternating in direction with each layer. They crisscross at 90 degrees to each other. Only a handful of companies–mostly American but some offshore– actually manufacture collector car tires and they make different models, some under license to Firestone, Goodyear, BFGoodrich, etc. Bias-ply tires have advantages over radials in ride steadiness, sidewall cut resistance, and repairability. Bias-plies cost less initially, too. They also have a self-cleaning property that radials don’t have. Still, their biggest advantage to collectors is their original-equipment look. Corky Coker calls that original appearance, “A concept that is foundational to our hobby, whether you have a completely original car or a customized street rod.”  He continues, “The bias-ply tire has and continues to provide utility service and aesthetic appeal for folks who desire a period look and originality. They are as safe and reliable–even more so today with modern materials–as they ever were and, let’s face it, we drove on bias-ply tires for over 70 years on much worse roads than we have today.”  


Benefits of Radial Tires

The plies on a radial run 90 degrees to the centerline, and overlap instead of crisscross.

The design of a radial tire allows the sidewall of the tire to be more flexible. This characteristic reduces rolling resistance, providing better gas mileage and longer tread life. This flex gives the radial tire a bigger footprint on the road so it grips better, and enhances both wet and dry handling.

The aspect ratio–the relationship of the height and width of the tire cavity–is another advantage of radials. Early tires were round and had a 100 percent aspect ratio. Later bias-ply tires had an 82 aspect ratio (the cavity height was 82 percent of the width). Lower profile 60, 78, and 70-series tires had wider footprints and shorter sidewalls. These factors produced a firmer ride and more responsive handling. Radial tires have an even shorter, wider profile.

As the aspect ratios decreased, tire makers used belts layered under the treads to provide better tread face integrity. These were originally fiberglass belts, but steel mesh belts were used later. Belted bias-ply tires were used in the 1960s, particularly on muscle cars, but now we think of steel-belted tires as radials. 

“A collector drives his car on radials, instead of the car driving him,” Coker told us.


“Best” Tires and “Right” Tires

For many car collectors today, that same question of whether to use bias-ply or radial tires on their classic car is still a big issue. Each of the major sellers of such tires–Coker, Kelsey, Lucas, Universal, Wallace W. Wade, and Diamond Back Classic Radials–seems to have their own answer. Actually, there are two issues concerning the use of radials on collector vehicles: One, are radial tires better? And two, are radial tires right for my classic car or truck?

Coker says, “Of course the radial is better. It’s the ‘new improved’ tire. In fact, it’s a better tire today than it was when it was first introduced as original equipment on the early 1970s Lincoln Continental. Its design is better for road and highway use, it is safer, and it provides higher gas mileage and longer tread life and much better handling.” 

Kelsey is more reluctant to pick one type of tire as “best” over the other. He says, “If your vintage auto was originally fitted with bias-ply tires, then they will do a fine job for you and return your vehicle to the original handling characteristics it possessed when new. Most people today have not driven on bias tires consistently–if ever–for many years. They are used to radial construction in conjunction with a highly designed radial suspension featuring concepts designed to provide you with a smooth ride in a vehicle 1,500 pounds lighter than your father’s 1955 Cadillac. The radial tire is a component of such designs.”

Maytag Smith of Lucas Classic Tires summed things up like this: “I don’t know if you can say one thing is better. Remember, these cars [that radials are available for] got to be up to 50 or 60 years old using bias-ply tires. Most of us don’t drive the old cars 20,000 miles a year, so we don’t get the advantages of using radials, but those that do drive over 20,000 miles should have a radial.”

While experts vary on which type of tire is best, all classic car tire providers understand that the best tire is not always the right tire for a collector car. Factors such as actual manufacturer, design, appearance, logos, historical authenticity, and what tire makers call “fitment” enter into the buying equation.


Real-World Experience: Bias-Ply versus Radial tires

Car collectors frequently talk about the different types of tires and how they “work” on different classic cars. Many prefer the look of bias-ply tires, and are used to the way they perform. Some say their cars only have the right stance and ride height when bias-ply tires are used. Others think that bias-ply tires are better for old wheel rims. Due to past problems that have now been solved, some owners still feel that radial whitewalls turn yellow, and bias-ply whitewalls are best.

“In the late 1970s, Chrysler buyers had the option of getting non-radial or radial tires, and I distinctly remember a customer coming into my dad’s tire store with a brand-new 1979 Chrysler and changing the bias-plies the dealer had ordered for radials,” recalls Kelsey. “Ten minutes later, he came back and said something was wrong with the car.”  Kelsey’s point was that people not used to radial handling might prefer bias-ply tires.

“If your vintage auto was originally fitted with bias, then bias will do a fine job for you and return your vehicle to the original handling characteristics it possessed when new,” Kelsey added. “When appropriate-sized radials are fitted to a car of the 1950s with power steering and a correctly restored suspension, then you will notice a somewhat softer ride and more positive cornering, and find that you are paying less attention to the steering wheel.”

The reason Kelsey specified power steering is that radials make a car harder to turn at low speeds or when parking, and all of the experts agreed this is true. It was even suggested that this could have a detrimental affect on the steering box. On the other side of the coin, at high speeds the radial tires will track better and prevent the car from wandering or “following” cracks or waviness in the surface of a road. With radials on collector cars you should run a minimum of 35-45 psi air pressure instead of following the owner’s manual,” Coker pointed out. “This will also help when it comes to steering.”  

Many collectors talk of cracked rims, and hubcaps flying off vintage cars with radial tires. “Radials hold the tread patch to the ground, and the carcass flexes more,” says Coker. “With heavier vintage cars, something has more stress and it is the rim. I don’t say it will ruin older rims because 10-gauge steel is still 10-gauge steel, but it doesn’t hurt to have them tested and checked. And I believe, yes, the circumferential inertia does pull more on the hubcaps.”

Kelsey doesn’t buy into that theory. “You don’t have to worry about flange cracking,” he says. “Go back to the days when everyone was mounting radials, and I never saw any problems with flange cracking or losing hubcaps.” He says that old wheels taken from salvage yard cars could cause problems. “You don’t know if they have been through a fire or a wreck, so do you want them on your car?” Kelsey says loose hubcaps may be due to bent attaching prongs, which can be repaired on older-style hubcaps using needle-nose pliers.

Chapman has written an article entitled “Stress on Rims: Radials vs. Bias-ply Tires” which appears on page 33 in his Diamond Back Classic Radials catalog. He believes that radials actually cause less stress on rims than the old “rigid” bias-ply tires, and he cites information from the Department of Transportation’s FMVSS 19 (Tread Act) to back his point of view.

Another real world question about vintage car wheels is whether they are suitable for use with tubeless tires. T-Series MG experts prefer radial tires on these cars (with much higher air pressures than the factory used in the early 1950s), but always warn that they should only be used in conjunction with tubes. “Remember, you can use radial tubes in a bias-ply tire,” warned Kelsey. “But you can’t use bias-ply tubes in a radial tire.”

As for yellowing white sidewalls and other quality issues, everyone agrees that there were many problems with the first radial tires that were made in the U.S., as well as problems with early wide whitewall radials. Coker told us, “The difference today is that our radial tires are designed from the start to be classic car tires; they are built from the start to be redlines or gold lines or whitewalls, and the colors are not cured on like others were.” Chapman has two articles in his catalog about whitewalls, one covering what ruins such tires and the other explaining why some radial whitewalls–like those he sells–don’t turn yellow. “We sell only radials,” he said. “And then only radials made by big companies.”


On the Horizon

Are there any high-tech new tire products coming down the pike for car collectors? Kelsey says he thrives on marketing a “short line” of models targeted to current market appeal. Kelsey’s 6.00x16 and 6.50x16 Deluxe All-Weather tires are a good example: They really look great on mid- to late-1930s cars, but you would not put them on a muscle car. These Goodyear Collector Series tires are in Kelsey’s Antique/Classic line. They are bias-ply tires with 4-ply poly construction and have a 3.5-inch whitewall. We have to agree with John’s claim that, “A late 1930s car restoration just isn’t complete without these.”

Wallace W. Wade and Lucas each stock a diverse line of tires from various manufacturers. When something new arrives on the market, they are likely to carry it and do a good job selling it to their clientele. Diamond Back Classic Radials, which Chapman launched in 1998 after selling the tire store he had worked in since the 1950s, is an aggressive marketer who is constantly bringing out new product. Coker is the largest supplier and told us of several exciting new products he is working on to fill the needs of collectors.

“I grew up around hot rods and collector cars, and I’m a car nut first and a manufacturer second,” says Corky. “Because of our relationship with BFGoodrich and Firestone, we are going back to fill in the fitment gaps that exist today. For the big Classics (cars recognized by the Classic Car Club of America such as Auburns, Cords, Duesenbergs, and Packards) we are in the process of building new Firestone models with 7.00- and 7.50-inch cross sections in 20- and 21-inch diameters. We also have new sizes coming for the nostalgia hot rodders who need ‘big-and-skinny’ tire sizes. “We distribute in 40 countries now and, believe it or not, we’re working on a 13-inch redline for high-performance Ford Falcons that they made in Australia.”

Coker says that he is already building “narrow profile” radials for vintage applications. “We developed a new line of drag racing tires and we do special one-off jobs like the tires we made for the 1940s GM Futurliner Parade of Progress bus, and a very special single set of tires for the Daimler Double Six,” he explained. “We have 75-100 new products on our development list–for here and Europe–at any given time. “We’re even working on German script military vehicle tires.”

As you can see, there are many good options in the market today for classic car collectors. New materials and new methods of production are making it easier to get tires for your vintage car, truck, or even motorcycle. And whether you prefer bias-ply tires or radials, there are products for you to buy that will make your car easier and safer to drive on modern highways.


SOURCES

Coker Tire
1317 Chestnut St.
Chattanooga, TN 37402
800-251-6336
www.coker.com

Denman Tire Corporation
400 Diehl South Road
Leavittsburg, OH 44430
800-334-5543
www.denmantire.com

Diamond Back Classic Radials
Conway, SC
4753 Highway 90
888-922-1642
www.dbtires.com

Kelsey Tire Company
1190 East Highway 54
Camdenton, MO 65020
800-325-0091
www.KelseyTire.com

Lucas Classic Tires (East)
2141 West Main St.
Springfield, OH 45504
800-735-0166
www.lucasclassictires.com

Lucas Classic Tires (West)
2850 Temple Ave.
Long Beach, CA 90806
800-952-4333
www.lucasclassictires.com

Universal Tires
2994 Elizabethtown Rd
Hershey, PA 17033
800-233-3827
www.universaltire.com

Wallace W. Wade
P.O. Box 560906
530 Regal Row
Dallas, TX 75247
800-666-TYRE
www.wallacewade.com

COMMENTS

Find Articles

Please select a field.

To

 GO
 

Advertisement

 

Magazines

Magazines

Put your passion into gear

From Customs, Chevys, Fords to the Classics, these magazines provide the latest cutting edge information to fuel your passion.

MODEL INFORMATION

Required Information

 GO