Radial Tires

[Bill Bickle 15098]

A question has arisen concerning installing Radial tires on bias ply tire rims; in my case on my 1940 LaSalle.  Is this a safety issue?

[Fred #23106]

I recently installed a set of radial-ply whitewall tires that were purchased from Diamond Back in SC.  They start off with 6 or 8-ply truck radial tires and vulcanize the whitewalls to the tire. This gives the sidewalls good support and the tires do not sag on the sides as much as radials normally do.  

The LaSalle rims have rivets and I was in hopes that the air would not leak around the rivets.  So we sandblasted the rims and painted with epoxy primer and then painted with acrylic enamel with hardener and the wheels came out great. All of the paint should also help stop any leaks.  This was over 3 months ago and no air has escaped as yet, although car has not been driven more than about 50 miles due to bad weather in Ohio.  I would call Diamond Back if you have any safety questions. They can be reached at 888-922-1642.

As to safety, the old bias tires had tubes and tubes can blow out. Once the industry went to radials, had less trouble with blowouts, so in theory the radials should be safer, although do not know if the older rims would cause any safety issues. I do know that many others on this forum have been using radials on their older Cadillacs and LaSalles with the older rims and to my knowledge, none have had any problems.  

In fact, one of the reasons that I went to radials, was that I felt they would be safer than bias tires. The big bonus is the difference in steering and handling, and without power steering, we need all of the help that we can get! If any problems occur later, I will be sure to report this on this forum.

Fred

[Don Boshara #594]

Ive had Diamond Backs on my 40 Cadillacs original rims for over 5 years and about 5500 miles and am very happy with them.

[Bill Bickle 15089]

Thanks guys for your input. I appreciate the comments.

[walt #23510]

 Hey guys,Ive known of ALOT of people putting radials on bias rims,and no problems whatsoever.However,not wanting to deviate from rims that were engineered for radial caused me to purchase a set of Chevy truck rims for my 1955Coupe.They are slightly wider,but do clear and work quite well...walt...tulsa,ok

[brian rachlin]

I have read a lot about this topic.  The radials handle and corner better, which tend to make a person push the car a little bit more.  Many people have written in to hobby publications and commenting on losing hubcaps due to wheel flex due to the higher load placed on the rim.

It is very important to check the structural integrity of your rims prior to installing radial tires, and I would recommend checking them again for fatigue or stress cracks after about 500 miles.

I know of many cars, from the 30s to the 70s running on wide white radials, and no problems, but it is best to check, and maybe even upgrade to a modern rim if possible, if your stock hubcaps will work.

The difference in handling is amazing, and well worth it in my opinion.

Brian

[Andrew Straw 21467]

Walt, are you able to use your stock 55 wheel covers on the Chevy rims?  This sounds like a good solution.

Andrew Straw 21467

[Greg Calkin 18288]

In early 2003, I installed a set of BF Goodrich bias ply tires on my 1940 7519. These tires (from Coker) required large weights to get them balanced. During the first 3,000 miles I had 2 flats, due to tubes splitting inside the tires. I began to understand why I needed the dual sidemounts. By 8,000 miles I experienced one more tube failure and the tread was half worn. The tires were installed properly. We could find no reason for the tubes splitting along lines on tubes.

At that point I decided to install a set of radials from Diamondback (Yokohama LT 750x16).  As soon as I released the emergency brake the car started to roll back due to the slight slope of the garage floor.  With the bias ply tires, I would have to push the car to get it to move.

I expected the car to steer harder in the driveway when at low speeds, but that didnt happen.  On the road I noticed that I didnt need to constantly move the steering wheel to keep the car on course and steering was much more responsive. The ride was slightly rougher especially with broken pavement and pot holes, but not that noticeable.  The constant tread noise that had been present at speeds over 20 mph was gone.  The car was much quieter than before.

On curved roads such as highway entrance / exit ramps the car handles much more safely.

I made one panic stop from 55 mph to avoid a deer. On wet pavement, the car stopped as straight and controllable as any modern vehicle.

With almost 8,000 miles on the radials, I have had no problems. The tires show little wear. My hubcaps have stayed in place. These tires hold pressure much better than on my modern car. My wheels had been restored to a factory look and sealed with a urethane paint so this helps no doubt.

The wide whitewalls still look as good as the day they were new. Since installing the radials Ive seen a 15percent improvement in fuel economy, but I cant be sure that its completely due to the tires.

The tubeless Yokohama wheel / tire combination weighs 67.8 lb, compared with 57.9 lb for the B F Goodrich.  This was surprising since the tube weighs 3 lb.  Despite the additional ten pounds, the radials require much smaller balance weights.

The BF Goodrich bias ply has a load rating of 1850 lb, whereas the Yokohama radial is rated at 2440 lb.

The Diamondback Yokohama tire looks much more like the original bias ply tires than many. The tread pattern is almost identical. The stiff sidewalls do not bulge at the recommended 50 psi. One model includes a raised ridge beauty ring on the outer edge of the whitewall.

[walt #23510]

Andrew,
 Yes,the 1955 hub caps do fit the rims,but they are VERY tight! Tight meaning hard to put on and take off.(havent lost any yet!)...walt..tulsa,ok