Re: What's the difference?

Posted by Loyd Smith On 2010/4/26 17:06:49

Although radials offer a generally (if sometimes marginally) better ride, better stopping ability, last longer under constant use than bias-ply tires and tend not to track road irregularities as readily the disparity, under most normal driving conditions and with properly maintained suspension and steering, are too slight to tell the difference. Too, the sidewalls of the radial are the weakest points in the construction of the tire. This is inherent in the radial design because the radial belts do not extend all the way to the inside mounting rim of the tire as they do in the bias-ply design. Modern materials and manufacturing techniques have eliminated this weakness to some degree but I will not mount a radial tire with less than an "H" rating on any of my vehicles for this reason.

The principal reason that we have radial tires, today, is that they're cheaper to manufacture than bias-ply tires.

I, too, have had bad experience with some modern repop bias-ply tires having bought a set from one of the most widely advertised sources for my Patrician. They were the proper wide whitewalls and looked great but they were so out of round that they couldn't be balanced. Upon taking them to my old tire guy to be trued (shaved), he advised me that the tread depth was so shallow that he'd rather not true them and wouldn't run them on his own vehicle after he did. As it turned out a friend with a mid-fifties Cadillac show car that is only driven on and off the trailer bought them from me, knowing that they weren't round and not caring one way or the other.

On the whole, I'd rather run bias-plies if I could be assured of their quality than I had radials but, in today's circumstances, generally run "H" rated radials on the Lincoln and the Packard as I drive both extensively.

Flat spots on bias-ply tires are generally caused by their having belts made of fibreglass or some other synthetic material rather than natural fibres. Most times the flat spots will work themselves out when the tire heats up. Sometimes, particularly when a vehicle sits for extended periods of time through cycles of temperature changes, they will become permanent. Back in 'the day' when all tires were made with cotton belts, flat spots were never a problem but, then, cotton belts won't take the punishment that modern synthetic materials will. It's a trade off.

On the whole I agree with PackardV8. Most of the tires made, worldwide, today come from the same seven or eight manufacturers and are made to pretty much uniform standards being simply 'branded' for whatever markets they're going to. As long as I can find correctly rated radial tires for the vehicles I have and the service I intend to put them to, I buy the cheapest ones that I can find that are closest to the OEM height and width. This is my practise for my 'drivers.' If I showed any cars and was likely to loose points in judging, I'd probably take a different tack.