Radial tires vs bias ply

[Gold Bird]

My Dad was reading a story in one of the old cars magazine today about not using radial tires on the old style rims of cars produced before 1965. They said not to use radials as they would fail. Has anyone heard this before, and what are your opinions on the matter. Thanks!

[byersmtrco]

Naaaaaaaaaa !!! My dad ran radials on the stock wheels for 30+ years. Never a problem.

Night and day difference in how you car will drive when you switch to radials. You'll never look back . . . nostalgia or not.
Coker and a few others (BFG) make nice looking wide whites (if that's your thing)

[Alexander]

I have heard stories of the edge of rims failing, but I suspect these rims were rusted.

I have been running radials on my Squarebirds for more than ten years with no problems.

[dgs]

I saw that same letter from an accident investigator in Old Cars Weekly. He made mention that Coker has something on their web site that supports his claim, but I couldn't find it. In fact, their FAQ section seemed to me to indicate it was a matter of preference.

It does make sense to me that the different construction of radial vs. bias would put different loads on the wheel lip. Many Squarebird owner has reported has reported loosing more wheel covers when radials were installed, indicating that more wheel flex is happening.

Is it dangerous? Well, lots of folks run radials on stock rims, bur anecdotal evidence of non-failure doesn't mean it's not risky. These cars may all be running closer to the load limit than the engineers of the day would be comfortable with. Alexander's point about rims in poor condition is a good one too.

I've got modern aluminum, wheels on mine, so it's no worry for me. If you want to run radials (and the benefit is clear), a set of 70's Ford 14" rims from the radial era is probably cheap insurance.

[Dan Leavens]

Goldbird I would agree with the group that have posted that radials are " night and day " difference on the ridability. I switched in the spring of this year to Coker's and not only had improved handling but the overall ride of the 58, was very noticable internally.

Dano Calgary,Alberta Canada

[Gold Bird]

Thanks to all for the info, I agree the ride is way better with the radials. My Dad was reading this article and got a little worried about having a tire blow or come off the rim. On the other hand the Cokers have been on the Bird for over 8 years and probably 10k miles and no problems. My 70 Trans Am has the original style Goodyear polyglass tires and it rides like a truck!

[dgs]

FWIW, i sent this to Coker today:

A recent letter to Old Cars Weekly indicated that it can be dangerous to install radial tires on wheels designed only for bias ply tires. As an engineer, and reviewing the construction differences, I can understand how a radial will load the wheel lip differently than a bias ply tire will, but is it dangerous? Is there anything definitive on the subject,
like say an industry publication from the 70's when radials were introduced regarding proper practices when using radials on older rims.

I have heard from many a Squarebird ('58-'60 Thunderbird) owner that having radials on meant tossing a wheel cover every now and then. Before I went to aluminum rims on mine, I threw a few wheel covers as well running radials. That indicates more wheel flex is happening, or at least it could.

The letter writer to Old Cars Weekly said he was an accident
investigator and that Coker Tire had some information on their web site to back up his claims. Nothing I found did so, in fact the 'radial vs. bias' article stated that it was a matter of preference.

As you are the leading manufacturer of tires for old cars, both bias and radials, I'd be interested in your take on this.

Later this afternoon, Jerry Preisel from Coker responded (which he gave me permission to post here):

Thank you for your recent inquiry into Coker Tire. The only that this can become dangerous is if the wheel is in bad shape, as long as the persons wheels are ok there is no danger. In regards to the hubcaps, they pop off because there is more flex in the sidewall of the tire and that works off the cap. If you have any other questions please feel free to contact me.

So there you have it.

BTW - Anyone know which issue of Old Cars Weekly it was in and what page? He asked and I don't have it anymore.

[Alexander]

His response makes sense. Sears started selling Michelin radials in the 1960's. Obviously, no American car at the time was designed for them. If there were failures of any sort, Sears marketing of the radials would not have grown so successfully that OEM manufacturers would start putting them as optional or standard equipment.

The Squarebird rims look just as beefy in the rim area as later rims.

[Guest]

Our cars have solid steel wheels. That i think are better steel than todays iron. Alexander is right that you don't want to use rusty rims. We don't drive these cars every day and keep up with the cooky cutters. Just my thought I think we are OK.

[dgs]

Alexander, I thought of that too. Many, many cars were built at the end of the bias era and later had radials installed as used cars. If there were safety concerns at the time radials were introduced, I would thing there would be several documents available from that era from tire manufacturers, tire store chains and car manufacturers warning of the danger. There would have also been a market for 'radial safe' wheels. If any of that happened, all of it seems to have disappeared now.

Also, aren't Thunderbird wheels different than standard Ford wheels? The regular Ford wheels has a kind of 4 spoke center, with 4 shallow slots between the wheel center and the rim while Thunderbird wheels were solid with no openings. I don't think that would make a difference in terms of the lip strength, unless the rim was a stronger or thicker steel.

Lastly, I did correct the guy on the wheel covers. Since Thunderbird wheel covers are significantly smaller than the wheel lip, there's really no way that the tire flex could push the covers off. I suspect that the wheel lip does flex more with radials, thus popping the covers. Unless you have a damaged wheel, however, the flex is not likely dangerous.

[Alexander]

I had plenty of wheel covers fall off my '59 when I was running bias-bly tires. One time, I found one of my covers that had cut fifty feet into a cornfirld. That inspired me to do the Sun Ray aplique modification. Nothng could make them fall off now.

[Gold Bird]

Very interesting information on the wheels, thanks to all for the help. I really like the way the car drives with the radials, I remember the bias ply tires would have flat spots after sitting for awhile too, rode like a truck for a few miles!

[byersmtrco]

Me thinks BF Goodrich T/A Radials are next for me. Just on which rims ?? I can't decide. Prob be baby moons.