Danger in running radials on a bias ply tire rim?

[Richard W.]

The Q&A column of the January 22 Old Cars Weekly (page 10) contains some issues that I do not remember seeing on the board. The question is in regard to running radials on a vehicle's original bias ply wheels. The article went on to say that a similar problem exists when disc brakes are used on vehicle retaining the bias ply wheels.

In summary, the article said that since radials have a different footprint and apply different forces those designed for the bias ply wheel, hubcaps can fly off, distort effecting handeling and ride and, in the worst case, break in 2 at speed. The article went on to say that even if you go back to bias ply tires (or drum brakes), the wheels are already weakened by the forces.

I have radials on my SWC's original wheels (I kept the drums based on advice from the Board and think they are fine) and have a couple of questions. First, am I exposing the car (and me) to undo safety risk? Second, if I should replace the wheels, who makes radial wheels that will have the proper design to hole my beautiful (and expensive) flipper wheel covers at speed (i.e. do they need some "bumps" or whatever?

Thanks for your response

[Roy B.]

Re: Danger in running radials on a bias ply tire r

For many years I have run Radials on stock bias wheels , Corvette or cars of the 50's Never have I had any trouble at any speed holding the caps on.

[Mike M.]

Re: Danger in running radials on a bias ply tire r

Richard i read that article the other day and had some reservations pertaining to some of the arthor's conclusions. I, like Roy, have run radials on my c-1 and c-2 rims for years and haven't experienced any stress fractures of either steel or alloy stock rims. however, i'll be on the lookout from now on.I don't think we are risking our lives running radials on rims designed for bias belted tires, as long as the tires aren't kumos or DOT drag tires that you are stressing unduely such as autocrossing or road racing.mike

[Christopher R.]

Re: Danger in running radials on a bias ply tire r

Most of the cars that are driven use radial tires. Thousands of car, probably millions of miles. I've never heard of wheels fracturing. To the extent that a radial tire does impart more stress on the wheel than a bias ply, it's nothing compared to the shock forces the wheel receives on bumps. You wanna talk dangerous? Drive around on bias ply tires.

Yes, the full wheel covers can come off. There is some speculation that the greater forces imparted by the radials causes the wheel to flex and allows the covers to come loose. I dunno. Maybe. But lots of people have no trouble with hubcaps coming off. I seem to remember that these things had a tendency to come off when they were new. Maybe it's something with the way they are secured to the wheel. Full covers are secured on the outside of the wheel by compressing the cover. The usual smaller hubcaps are secured closer to the center by making expanding the cover.

[Duke W.]

Re: Danger in running radials on a bias ply tire r

Pure unadulterated drivel!!! I wonder where the mags dig up these guys and who the heck is editing the crummy rag. As long as the rim flange section is designed to the J, JK, or JJ standard promulgated by The Tire and Rim Association, a radial tire is okay. (The wheel flange design should be in the AMA specs for your year.)

I did some ungodly things with my SWC from the time I installed radials in 1964, and never lost a wheel cover, though I did remove them when I hot lapped race tracks.

The one issue with radials is that all modern radials (that I'm aware of) are designed for tubeless tire wheels, so there may be a problem fitting them to older tube type wheels.

I can't remember when the C1s went to tubeless tires, but maybe someone else has the answer, but any Corvette wheel that was originally equipped with a tubeless bias ply will work successfully with a tubeless radial.

The Michelin X radials I installed in '64 were tube type, so I ran tubes with them mounted on the OE '63 wheels, which are designed for tubeless tires. Those Michelins lasted 47,000 miles including several hundred miles of race track hot lapping and a couple of trips to 150+ MPH.

The reason why you have not see these issues on this Board is because no one has ever had a problem that they say can happen.

You should cancel your subscription before it fills your head with myths and gobbledygook.

Duke

Duke

[Richard W.]

Thanks to all for your responses...

one less thing to worry about.

Thanks again.

[Dick W.]

Re: Danger in running radials on a bias ply tire r

I think that there is a h..l of a lot more danger running "quick fall off" wheels on a mid year than there is running radials on a C-1 or C-2

[Joe L.]

Re: Danger in running radials on a bias ply tire r

Richard-------

I agree with all of thew other responders; I don't think that there's any problem using radial tires on wheels originally used with bias ply tires. However, I'll offer an interesting observation:

1969-82 Corvettes with steel wheels all used an 8 X 15 rally wheel all coded "AZ". 1969-72 were originally equipped with bias ply tires and 73-82 were equipped with radial tires. This would seem to provide support for the fact that GM considered the same wheel applicable to both bias ply and radial tires. However, it's not that simple. The wheel used for 1969 through 1972 Corvettes was GM #3952869 (SERVICE GM #3970532). The wheel used for 1973 (the year that radial tires for Corvettes began) through 1982 Corvettes was GM #327709 (SERVICE GM #327708). I wonder why the change, particularly at the time that it occurred?

The GM #327708 replaced the GM #3970532 for SERVICE when that wheel was discontinued in March, 1973. So, we know, for sure, that there is REARWARD compatibility of the GM #327708 with original GM #3970532 applications. What we don't know, for sure, is whether there is FORWARD compatibility of GM #3970532 with original GM #327708 applications. We can surmise that, but we DON'T KNOW that.

[Chas Kingston]

Re: How do you REALLY feel, Duke? *NM*

[Ralph Harlan]

Re: Danger in running radials on a bias ply tire r

Back in the '60s when we did the parking lot races at the local mall, contestants would run radials for the traction advantage. To give a little more perceived "advantage" drivers would lower the tire pressure to below 20#. Many times the radials were installed tubeless. The only problems I was ever aware of resulted in the radial tire "rolling off" of the rim when cornered hard with low air pressure. Suddenly you were in a tight corner with one (or two) flat tires. Yep, hubcaps came off then, whether they were "full" caps or the "dogbowls" like I had on my '64 (didn't do much for your times, either). The CORVETTE CHARLESTON club - by the early '70s - restricted the use of radial tires for such racing to those mounted with tubes so that the tires didn't go flat in hard cornering when the tire bead "rolled" or was pushed from the rim.

[Duke W.]

Re: Danger in running radials on a bias ply tire r

I don't know why guys would lower tire pressures on radials. Back then with tall soft sidewalls the radials would deflect more than bias plys, which slowed steering response and reduced grip.

I ended up running my 6.70-15 Michelin Xs at 45 psi front, 50 psi rear. The steering response was instantaneous and precise with more grip than anything except a racing tire.

Back then tires were not placarded with maximum pressure, so who knows if my pressures were to high, but the performance was certainly there and I never had a problem with those tires.

Duke

[Duke W.]

Re: Danger in running radials on a bias ply tire r

Did the flange contour design (J, JJ, JK, etc.) change.

Duke

[Joe L.]

Re: Danger in running radials on a bias ply tire r

Duke------

No, the flange design was the same for all and is "JJ".

[Dave Suesz]

I guess I'm going to H***...

Because I put 300k+ miles on a set of '66 riveted 14x5.5 wheels using radial tires, and never even lost a trim ring.

[Rob Dame]

Re: Danger in running radials on a bias ply tire r

There has been some talk of the wheel covers rotating on the rim with radial tires causing the wheel cover to cut the valve stem.
When I put radials on my 56 I asked some questions here and was advised to use metal valve stems. This also keeps the caps from rotating off the wheel nubs.

It was advise worth asking for.
The radials made it feel like a different car and without a doubt I'd do it again. In fact I should have put them on sooner. I have over 2000 miles on them now I have not lost a wheel cover.Then again I don't thrash it too bad either.

Rob