Original Bias vs Radial Ply Tires
I am restoring a 54. I am at the point of puchasing tires. Both Orig. Bias ply tires and Radial tires are available in wide whitewall. I have heard the Radial tire improves the handling of the car enormously, but they can cause excessive wear in the steering box. I don't plan on putting a lot of miles on the car - but I hate to subject it to unecessary wear, and sidewall of a Bias Ply tire is destinctive. The cost differential is unconsequential. Anyone with experience along these lines - I would appreciate your comments.
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Re: Original Bias vs Radial Ply Tires
I've never heard the "excessive wear in the steering box" story, and I see no engineering reason for this to be the case, so my conclusion is that it's just another internet myth/conspiracy theory. The world is full of them.
Radial tires should yield better handling in the form of more precise and responsive steering, equivalent lateral force at a lower slip angle, and better straight line tracking on uneven roads, but if you plan on having your car judged, they will loose more points than a proper brand bias ply repro tire. My recommendation for those who want to both drive and have their car judged is to buy a second set of (generic) wheels - the originals for judging with bias plys and the generics with radials for driving. Or you can live with the bias plys until you finish your judging program, then remove and sell them and install radials.
The closest modern radial size to the OE 6.70-15 that is available in a suitable whitewall is 205/75R-15. All these sizes are either S or T rated and lack a safety enhancing spiral-wrapped nylon cap belt that is standard construction in H and above rated tires, but they should be okay for normal driving.
Use tire pressures in the range of 24-32 psi, cold. Higher pressure will improve all the radial tire qualities mentioned above, but the ride will be a little harsher. Run the pressure as high as you can stand in this range, and even if you run it at 32 the radial ride will likey be less harsh than with bias ply tires at the same or even lower pressure.
The only other consideration is to run less toe-in - nominally about 1/16" total, which is 1/32" per wheel. The spec for bias ply tires is typically about 1/4", nominal. You can also get away with minimum caster, which will reduce steering effort. Radials have greater self-aligning torque than bias-plys, so they don't need as much caster to have good returnability.
DukeLast edited by Duke W.; April 16, 2012, 03:27 PM. -
Re: Original Bias vs Radial Ply Tires
What duke said!65 350 TI CONV 67 J56 435 CONV,67,390/AIR CONV,70 454/air CONV,
What A MAN WON'T SPEND TO GIVE HIS ASS A RIDEComment
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Re: Original Bias vs Radial Ply Tires
Duke - thanks for the feedback. I don't plan to have the car judged - I've been through that scene with my 58. I am building this car to show at the occasional benefit show but mostly to drive and enjoy. My better judgement tells me to put the Radials on (my 58 runs on bias tires - I know how they handle - using the word "handle" loosely ) but I'm having a hard time abandoning the Bias tire look and I don't want to spend the money to mount both. What a quandry. Thanks for your input and tech. info. your advise is right on.
JohnComment
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Re: Original Bias vs Radial Ply Tires
If you don't plan on having it judged, I wouldn't put bias ply tires on it even if they were free.Comment
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Re: Original Bias vs Radial Ply Tires
I would agree with that, bias ply is only for looks (and if you enjoy flat spotting kathump-kathump), they are so much worse driving tires than radials on old cars, it isn't even close.Big Tanks In the High Mountains of New MexicoComment
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Re: Original Bias vs Radial Ply Tires
OK - Radials it will be. Now I have a real problem - if they perform as good as everyone emplies - I'll have to buy a set for the 58 ?
Everyone - Thanks for your feedback
JohnComment
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