RADIAL TIRES ON BIAS PLY WHEELS
submitted by Frank Moro
written by Tom Brownell in Old Cars Weekly (1/22/04)
[Here’s a Q&A article that appeared in the January 22 issue of Old Cars Weekly. The subject of radial tires used on bias ply wheels is most interesting. I know many old car owners have switched to radials with satisfactory results. I have considered radials for improved road control and stability. However, now I’m not so sure. - Frank Moro]
Q. Lee Oliver’s problem with his 1966 Plymouth Fury throwing hubcaps is much more serious than rim flex and lost hubcaps. Try losing your life with this problem! Rims for bias ply tires, radial ply tires, even disc brake rims are made out of different alloys. Rims for bias ply tires cannot use radials, and bias and simple radial ply rims cannot be used for disc brakes. The forces exerted by bias vs. radial ply tires (as well as disc brakes) are different and need rims made for them.
In Mr. Oliver’s case, he is using radial tires on bias ply rims. The rims over flex as they are unable to handle the forces of the radial tires. This over flexing also means metal fatigue, breakage (most commonly rim bead edge separation), and deadly accidents. Many will disagree, touting their successful usage of radial tires on bias ply rims, but as a fatal accident investigator, the first place I looked in any older car accident was at the rims.
Mr. Oliver is advised to immediately change the rims on his Fury. He should do this even if he returns to bias ply tires. By his own description, the rims are already seriously fatigued and severely weakened by this over flexing, and rim separation is next.
One can tell bias, radial, and disc brake rims by their markings, which is an easier way for Mr. Oliver to make sure his new rims come from a car for which radial tires were standard equipment. Sam Egan, La Mesa, CA
A. Thank you for the warning about running radial tires on rims designed for bias ply tires. A number of readers responded to Lee Oliver’s wheel flex and lost hubcap problem, several mentioning the need to change rims.
Dave Wilcox writes, “When you install a radial tire on an old rim and the footprint of the tire is wider or equal to the rim bead, the twisting of the sidewalls puts undue stress on the lighter and original rim. We put radial tires on our 1956 Ford and had the same problem. We cured the problem when we switched to 1966 Ford rims, which are one inch wider and eight to nine pounds heavier, which makes them stronger than the old rims.”
Paul Haase of Waterloo, IA, also advises replacing the rims. Then if the wheel discs still slip they can be held in place with a bead of silicone. Mr. Haase invites Mr. Oliver to join a Mopar or Plymouth Fury club for helpful technical information, such as locating the proper rims for his 1966 Fury. He recommends the Plymouth Barracuda Owners Club, 4825 Indian Trail Rd., Northampton, PA 18067, which covers 1964-74 Plymouths.
The rims on Chuck Holmes’ Willys cracked after he installed radial tires, clear evidence of metal fatigue. Unfortunately, Mr. Holmes is using one of the cracked rims as a spare - not a good idea.
Sanford Danziger recommends locating a set of alloy rims, which would obviate the hubcap problem.
To hold the wheel covers in place, assuming movement is still a problem with the correct rims, Dan Reed says he secured the wheel covers for his 1956 Cadillac with a strap that was secured by one of the lug nuts. He found this idea on a 1958 Oldsmobile. The strap has to be long enough to allow access to the lug nuts. It won’t prevent the wheel cover from coming off, but will keep it from being lost.
Marilyn Robinson says she ended the flying wheel covers on her Plymouth Valiants by switching to hubcaps.
Terry Wallace of Pensacola, FL, brushed some of the grit coating used on surf– and skate-boards onto the rim area that the wheel covers contact. The covers still wanted to walk on the rim, so he added a further bead of silicone and has had no further problem.
Bob Brooks of Suffield, CT, coated the wheel rim contact area on his 1952 Mercury with rubber cement and hasn’t thrown a wheel cover since.
To hold the full disc wheel covers on his 1989 Thunderbird, Lou Frueh of Wickliffe, KY, drilled a hole in the wheel cover 180 degrees from the valve stem, then drilled and tapped a hole in the wheel as near the rim as possible, and bolted on the wheel covers. He disguised the bolt to look loke another valve stem.
Robert Wittren of San Leandro, CA, finds that the wheel covers on his 1970 Duster with radial tires begin to squeak when the paint on the rim wears through. His rims are black and he keeps the wear spots touched up with Rustoleum.
Thomas Murray, also of San Leandro, finds that a strip of masking tape around the rim holds the wheel covers in place on his two Kaisers.
Bob Lewis of Susanville, CA, keeps the full disc wheel covers from moving on his 1950 Ford Club Coupe with a bead of silicone adhesive sealant.
Gerald White of Altoona, FL, observes that the brake drum will keep the center of the wheel from flexing, but not the rim, leading us back to Mr. Egan’s warning about the danger of wheel failure unless the rims are replaced by stronger ones designed for use with radial tires.