Technical Difference between Bias-Ply and Radial

Well thanks for everyone's input. Gonna stick with the Bias tires

 

I was running radial tires back in 1961. They were in the market place, but people just weren't aware how much better they were for handling than biased ply tires.
I even put radials on a 61 Pontiac, without making any other changes, and instead of having to aim the car, it could be driven on the highway with precision, and the cornering ability was markedly improved.
I don't care what anyone else runs, but for handling safety on the highway, I want radials.
Bob

 

they look like bias........they handle like a radial............

 

I hear you, but while it probably wasn't common in those days (1961 ?), were you actually running radials on what at that time were commonly considered "Hot Rods" ? Just curious.

I have nothing against radials, I think they're great. I've ran them on most of my DD's for nearly 40 years now, but on my vintage cars I just personally prefer the "real" period correct/vintage ride feel and IMO, most "modernizations" I referred earlier take away from that feeling and in my mind, essentially defeats the purpose of vintage driving experience.

Mind you, while I wasn't born quite by 1961 yet, in last 4 decades I've driven hundreds of thousands of miles with all kinds of vintage cars from 1920's to let's say early '70s, some even on public roads at speeds exceeding 140 MPH and rarely, if ever felt any more unsafe than in modern cars. My 86 year old Roadster has some (more modern ?) running gear upgrades dating to late '40s and early '50s, but I feel it would loose its "character" (or soul, if you will ?) as an early fifties (period correct ?) Hot Rod if any of it got replaced with something not yet available at that time.
(Full disclosure: My Roadster has 2-point (lap) seat belts, which often makes me laugh as they likely wouldn't provide practical protection in case of any collision and in case of a roll-over, it would probably be safer to be un-strapped and hopefully get thrown out it.)

If I preferred or wanted a "modern" ride feel, I'd just get ride off my vintage cars and go shopping for the latest and greatest local dealerships have on offer or buy a kit car incorporating all that "modernism".

 

Here we go ....... again.

 

I amost feel like the argument against radial tires is akin to saying that you should only use oil manufactured before 1965. Tires are meant to wear out. They are consumables. Same with belts, hoses, etc. I think there is a pretty distinct line between say, digital gauges and radial tires. Admittedly, I only drove on bias ply tires for a short period of time. They made the car difficult to stear at highway speeds, but those tires were worn out. For me it wasn't an option anyway as $60 per tire is more my price range than $200.

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

I've got addicted to modern low-profile radials. After running 50-series tyres on my DD for years I'd have trouble going back to tall-profile radials, never mind crossplies. I'd expect that you'd run into a diminishing-returns type of situation beyond about a 45-series tyre, though.

It's all about your philosophy of history, though. To claim that it is invalid to want modern high-performance tyres while simultaneously emphatically not wanting all the other characteristics of the typical new car presupposes a few ideas, all of which are disputable, e.g.

• that history works in a linear manner, i.e. that any given set of circumstances can only have a single outcome: an idea which has implications for human freedom and agency, which implications I'm not sure I'd like to embrace;
• that simultaneous contradictory paradigms cannot exist and that any artifact which comes into existence in the presence of a paradigm which predominates at any given time must therefore be an embodiment of that paradigm, i.e. tyres designed in a cybernetic-dominated age must be cybernetic tyres (what on earth would a cybernetic tyre be?);
• that the only valid interest in a historical paradigm must arise from the affirmation of a coherent concept of the corresponding historical era, which implies that historical eras themselves are a specific sort of real thing;
• I could go on.

 

And now we've gone around in a circle and what's the best answer? Bias ply looking radials? The Coker offerings look okay and I could see using their Excelsior Stahl Sport Radials. Diamond Back Tires have a better looking product with their Auburn Deluxe Radials, but with only 2 sizes currently offered (600R16 & 820R15) they don't have a big 'n little set I'd be interested in. As said before, oh well...,
-Dave

 

I wonder why the industry switched to mostly radials to begin with? Usually its profit motivated. Planned obslecence radials go bad after about 7 years? I Have bias plys that are 45 + years old on my 66 ford F600. They where recaps that I bought from my Father in law when I was dating my wife. So I don't know how old the casings are?

 

I think the expiry date on tyres is a new thing, not necessarily radial-specific.

 

Manufacturing date coding on (some) tires existed in the 1970s and might've been around already in the '60s.
Back then and thru '80s. it was only three digits, month & year (without the decade).
I could be mistaken, but the fourth digit (decade) might've been introduced in the '90s. It has definitely been around throughout the new millennia and has been a mandated by USDOT & EU regulations on all types of (passenger car & small truck/van/SUV) tires for at least quarter century now.

 

As far as I could discover, the four-digit code comprises two digits for the week, i.e. 00 - 52, and two digits for the year. I don't know about earlier forms.

I also read that the importance of this arose out of legislated changes to the vulcanizing process chemistry, which resulted in less durable rubber. That may or may not be true. Economically, I'd expect that the process would be quite volume-dependent, which implies an incentive to reduce product life.

 

Radials wear longer, but they sure don't last as long.

There is some pressure (no pun intended) for mandatory tire replacement by law every X number of years. As it is now many tire shops won't even touch a 10 year old tire, they won't mount them or balance them. Most often the number put out for this legislation is every 6 years. The last set I bought were already 2 years based on the date code. If the gubbmint does this one thing that will happen is tires will get expensive. I mean, more than they already are.

 

The difference.....one looks better on traditional HOT RODS.....the other are usually more round.

 

Radials wear longer, but they sure don't last as long. That's importiant to decision making. If you only drive a small number of miles per year ? A bias ply might fiscally be the better choice.

 

Forgive my ignorance, but do bias-plies have the 7 year shelf life that radials do? The Denman's on my car currently are 16 years old. They are just beginning to develop some cracks in the tread and the white wall.

 

There will be lots of conjecture and lots of opinion on this thread as always.

Here is fact, radials are worn out long before the tread is gone. The way you can tell is that you will think you need to rebuild your suspension. New tires and the suspension comes back.

Fact if your suspension is not designed for radial tires you will actually corner and stop worse then with Bias plys. Nothing that you can feel in the seat of your pants but it is skid pad proven. Drag racers that go from Bias ply to radial slicks notice a difference that can be felt in the seat of the pants or the staging lanes.

Fact radials only get better mileage if you run them hard, they also last longer that way. If you run dirt roads at all it is a must, they will pick up sharp pieces of flint and puncture.

Fact bias ply tires and radial tires perform differently. Neither is better than the other you just have to drive differently.

Fact good bias ply tires are harder to find and more costly. Cheap bias ply tires are not good performers.

Fact the wrong bias ply tire looks as hokey on one of our style of car as a radial, think M/T Sporstman here.

After that it is all a matter of choice. I am running radials on my current project until I can afford the tires that will be correct for it. I own the radials and my choice is based on my wallet. But hopefully that will change with time.

Depends on the rubber compound used and care. Example, the @raven went 128 @12.3 on 40 year old bias ply truck tires. They were hard as a brick it was like driving the little T on ice and he drove it on those tires everyday for about 5 years. His brand new bias ply ribbed front runners did not hold up as well. They were a modern rubber compound which was softer and more susceptible to the elements. You do need to make sure that your old bias ply tires are not weather cracked and if you are running recaps that all goes straight out the window.

 

Tire life expectancy has a lot to do with location. Direct sunlight is not good for rubber. When the studies were done they picked Arizona. So I think it's skewed a bit. If the car is garaged they should do a whole lot better. You're probably fine, but it depends on intended use, I wouldn't want to take a cross country highway trip in the summer with 16 year old tires. I've done it but it's not my preference. Older tires the rubber tread and sidewall gets stiffer and it's not so noticeable because it's gradual. They don't grip on wet road nearly as well.

Radials have steel belts. I'm not sure exactly how it would get in but if moisture collects around the belts they will corrode, that's one theory of why radials fail earlier. Often on a long run in high temperatures. It stands to reason if that's true a radial will do better over time if parked on concrete than in the mud.

 

Care to offer proof for these "facts", as they seem somewhat contradictory to my (limited) experience and research ?

Sounds more like a fairytale "theory" created by someone with no knowledge or understanding how tires are constructed.

The aforementioned (5-6 year) manufacturers liabilities and warranties extend to both, bias-ply and radial tires intended for road use on cars & small trucks (incl. SUVs).

OTOH, anyone can drive with as old tires as they want, but everthing else being equal, they will not receive same quality performance from 10, 25 or 40+ years old tires as they will from, let's say, 4 year old ones, regardless of structural design.
All I can do is hope those idiots stay clear from the roads or streets I'm traveling on.

Even after dozen+ years, I still shudder when thinking about the time when a (new at the time) client brought a (at the time) almost 35 years old sports car capable of 170+ MPH to my shop for some deferred maintenance. The ("like new" ?!?) tires it had at the time were nearly 30 years old tires and had sidewall cracks so big I could put my index finger in them. He actually drove it to my shop and expected (almost insisted) me to take it for extended, high speed test drive before starting to work on it. Obviously I refused, but now 12+ years later, I'm still looking after the car for him and actually (test!?!) drove it at 140+ MPH (again) few weeks ago after its most recent services

 

Radials worn out before the tread is gone? I dunno know about worn out. But take a look at any junk tire pile. You will see plenty of radials that have failed (belts broke punctures that cant be fixed ect) that still have plenty of tread. And in that same junk tire pile the bias plys will be worn slick. Ive seen plenty of Bias plys that are worn down to the cord and still holding air. I reciently had a decade old bias ply rough tread. I mounted it in a split rim with a new tube. Hauling a heavy load the tread began coming off from the casing. Probably about 40% of the tread came off?
But it made it all the way home & I changed it. But it is still fully inflated. Let me see a Radial do that!

 

Ok heres pictures of the rough tread that made it home. I was going slow about 40 but it never really shook or anything. The 4th &5th picture are of a old 8 ply that was on a trailer and also never went flat. The 6th is of a decades old 16 inch bias recap on the front of a tricycle front end tractor. The 7th is the 8.25 x20 recaps I bought from my wifes daddy when we where dating. Our 45th anniversary is the 24 of this month. on the rear of my 66 ford F 600 worn smooth but still holding air never been flat. and the last picture is of a radial that blew out on a setting vehicle not even moving. When it comes to used tires I will pick a bias ply everytime.

 

Those 'tire expirations' came out of the Ford/Firestone tire debacle. Yes, the study was done in Phoenix, which has the highest average daily temperatures of any urban area in the US. Yes, heat/UV exposure contributes to rubber degradation. One thing from the full report should be noted; the heat effect is exponential (i.e. as heat goes up, the RATE of degradation also goes up), so if you live in a more temperate climate your tires will degrade much slower. Six years in Phoenix is NOT the same as six years in Seattle, Detroit, or New York. This is the main reason why the nannies haven't managed to get a law passed.

Second, you won't find even one manufacturer (cars or tires) that will unequivocally state that their tires will become 'unsafe' on a magical date. They merely 'recommend' that you have them checked by a 'technician'... you know, that kid at the tire store who only looks at the tire date code then pronounces them 'unsafe' and would you like a price on some new ones?

And in spite of all the antidotal 'evidence' found various places, the NHTSA was unable to find even one reportable accident that could be blamed on tire age, and they searched all fifty states. Underinflation/overloading is the leading cause of tire failure, followed by road hazards.

And yes, leaving a tire in long-term contact with earth WILL degrade it. The organics in the soil will attack the rubber. Parking on gravel or pavement will prevent this.

 

Why the scare quotes? It sounds plausible though I don't claim any special tire construction expertise. Why do bias-ply tires last years and years and years till they're bald, but radials shit the bed? About 10 seconds on Goolag search shows tire manufacturers point to moisture contamination of the steel during manufacturing, as well as improper plug type repairs allowing water to get in. Corrosion of the steel belts can cause tread separation, so it makes sense to figure out how different ways that might happen. Are the steel belts positively air and watertight through their service life? Heck if I know.

 

My opinion is the wire is wrapped and when it gets to the individual wire ends the only thing holding the ends in place is the rubber. And once one strand of the wire becomes loose the shifting accelerates and the belts squirm and the radial tire comes apart. Also any puncture that breaks a wire or more its just that many more wires that are not held by anything but the rubber. Change the direction of rotation on a radial and it will often fail very quickly. The picture I posted showing the radial that blew just setting. The wires are rusty. But its been raining and that tire has been outside for a month. They weren't rusty when I pulled it off the vehicle.

 

1998 MOPAR Muscle Magazine did road tests, skid past tests and track tests using muscle cars (whose suspensions would surpass those that we use) bias wide ovals V radials performance tires. Professional and magazine staff driving. They discovered that the then obsolete muscle car suspension was not up to the task of the difference in bite characteristics of the radial tire, and without proper tuning (IE spring and shock changes) would collapse under the stress of the more modern tire.

As for drag racing going from bias slicks to radial slicks you are going to have to get off your ass and into the pits at any track and ask anyone who actually knows what they are talking about. Give that you do not accept me as one who knows. You have to completely retune your suspension for the radial up to and including using different spring rates.

Now compound that by the fact that we are often mounting the tires on an obsolete 60+ year old wheel, no safety beads should be your first clue, but if that gets passed you consider the wheel center flexing as the radial gets enough more bite to collapse the more modern muscle car suspension, yes better bite but wheel flex will kill you.

Running them hard in the dirt? You are just going to have to accept 40+ years of experience on and off the pavement.

Now let me add a little more information. The early Ford Explorer was experiencing tire failure, Ford tried to blame it on Bridgestone tires being faulty. The NTSB along with Bridgestone did their own testing. The recommended tire pressures by Ford were below that which was suggested by the tire manufacturer. Ford dropped the tire pressure to overcome the poor ride characteristics of the Explorer, the radial tire failure was determined by the NTSB study to be caused by heat build up accredited to the lower tire pressure. Uh what is one thing we do to our old cars to make them ride better?

I am not Nader-esc I am just stating what I have learned from actual research done on my part. Maybe you should consider doing a little of your own leg work.

Oh and you did not question the 12.3 on the old skinny 6 ply truck tires. Ryan has the paperwork to prove that.

 

My '64 convertible had new bias ply tires and stock drum brakes when I first got it. Stopping distance was horrible. I swapped to radials and disc brakes. There is one kid who is ALIVE today because of it. He was stupid and thought he could beat traffic on his bicycle - being young and dumb he made a bad decision - but make no mistake about it, radial tires combined with disc brakes saved his life.

 

While I respect your likely longer experience than I have with motor vehicles and their tires, I do have to admit I fail to see the logic offering this as an argument or defense on behalf of one choice (bias-ply vs. radial) in a case where some one (OP ?) is considering new replacements for their vintage vehicle.

 

I think my argument works well. Of course you are not one to listen to fact over conjecture.

Now tit for tat my friend offer some proof to back up your beliefs.