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Thanks for the info on the Coker bias ply tires, and their website. I'm afraid to look, because I might buy something!

I need to note, for clarity, that Bias Belted tires were not only available, but quite popular back in the day. I imagine somebody (maybe Coker even) is still making them as "authentic" 60s and 70s repros. They generally had two bias plies and two belts.

Bias Belted tires were generally crap. One reason was that the belts tended to loosen up and then shift around inside the tire while you were driving. Fun, huh?

The theory behind making these tires was, I suppose, that the more flexible 2-ply sidewalls of the Bias Belted tires would help cornering, mimicking radials by allowing a bigger footprint through the turn. The results were, to say the least, questionable.

More on the tire saga:

I took the car out for a Sunday spin yesterday and wound up on some horribly potholed and grooved, damaged pavement (if you could even call it that). Bounced around like crazy, even at low speeds, but never felt out of control (well, maybe a little).

I had luckily just checked the manual for tire pressure on the '54, and decided for once in my life to put in something close to the recommended pressure (I usually run right up to the max pressure on the tire, theorizing that the auto manufacturer's recommendations are usually specified to improve ride, not handling or gas mileage.)

The car got through it with no noticeable damage or extra clunks or rattles, but the AMAZING thing was that the tires, which had been given a death sentence by my mechanic, went through it with aplomb.

The mechanic had said, as I mentioned, that the back sides of the tires were badly cracked. I envisioned deep fissures. Running my fingers over them, I could feel no cracks or bulges.

The mechanic gave me the news on the tires after he had removed the wheels from the car to do brakes. (As I think I also mentioned, he had given them a clean bill of health just two years and about 400 miles ago.)

Included on my work order for this last visit was re-mounting the tires and clean up the rims.

MY THEORY IS that the change in the mechanic's diagnosis of the tires was because he did not want the liability of being the last one to work with them prior to a blowout and subsequent damage to me or the car.

Am I right in thinking that these tires, which are very good examples of '70's or early '80's' 4-ply polyester bias ply tires, still have a lot of miles in them? Like 4000 or so? They have almost-new tread, and the sidewalls are, to me, quite acceptable. They are Cooper "Untouchables" by name.

I want to keep them, but will also listen to carefully to contrary (or supportive) arguments/suggestions.

Here in Michigan the roads are so dilapidated and hazardous that I run 10% below the recommended tire pressure.

I'd rather replace tires that have my suspension and powertrain beaten to a pulp.

Tim Cole wrote:
Here in Michigan the roads are so dilapidated and hazardous that I run 10% below the recommended tire pressure.

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Tim,

Interesting observation, but my tires are the kind originally specced for the car (tubeless bias ply), and I don't think they beat the suspension and powertrain any more than other tires might, except possibly radials, which I hesitate to use. I don't think I broke any springs, or sprung any leaks, on my adventure. In fact, with power steering, the car behaved rather nicely.

How would you say the 4-ply bias tires stand up structurally?

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Am I right in thinking that these tires, which are very good examples of '70's or early '80's' 4-ply polyester bias ply tires, still have a lot of miles in them? Like 4000 or so? They have almost-new tread, and the sidewalls are, to me, quite acceptable. They are Cooper "Untouchables" by name.

I want to keep them, but will also listen carefully to contrary (or supportive) arguments/suggestions.

Just looking for feedback on using these good ol' tires.

Ten or twelve years should be the age limit on tires. If you get about 1,000 miles worth of fun out of your car per year that would bring the tread life of a biased tire right to it's end.
I replaced the Coker tires for my '60 Buick at 11 years and 11,000 miles. They were not rotted or bald. I figured I would replace them before they got dangerous.

You can save $200-$250 on a set of Coker tires if you buy them through Summit Racing. Summit has a hair better pricing and free shipping.
Bernie

Thanks Ima48to for the tip about summit racing and coker tires.

Steve......

A tire engineer esplained it to me this way.
Modern tires are designed to last for previously unheard of miles.The trade off is that the shelf life of the materials is rather limited.(Unlike the liability)
Old tires lasted for a great many years but you did not get the miles out of them.
Would I put the wife & kids (or any major load) in the car with old tires & cracked sidewalls & head for the Bad Lands? No. Would I & a passenger hit the Interstate @ 75? Air up the spare & giver 'er!

A lot depends on how the vehicle is used. Radials are more prone to tread separation than bias ply tires. If the car is not driven at highway speeds catastrophic tire failure is unlikely. The increased demand on a tire due to speed increases as a square of the change in velocity.

Tires are the first tier of the suspension system. If they are filled with concrete to reduce rolling resistance then no road shock will be absorbed by the tires. The result is accelerated wear on the suspension and powertrain. The same is true of running sky high pressures.

Sure running lower tire pressure in my car because the roads in Michigan are unsafe will cause accelerated tire wear and lower fuel mileage. However, the roads are not safe and so I don't drive at high speeds. If I'm in a state with safe roads I'll raise the pressures to what is specified.

Thanks for the great feedback. Whatever I do, I will not make anyone beholden for the results just because I happen to follow, or not follow, their advice. The final result is on me.

I will say this. I entirely agree that the shelf-life of modern tires is much shorter. It may be because of the compound or because they can get away with different processes because tires get sold and used up so fast due to how quickly we put miles on them these days.

As far as what I've got on there now, I can only say that I have flogged the heck out of them, with continuous highway speeds up to 70 mph, potholes, hard cornering, the works. I did this partly to give them a good test. Of course, also partly because it was fun and gave me an excuse to let 'er rip.

I'm going to go shopping and see what's out there. It's nice that the old ones are still holding out (so far) while I do that. Thanks for the tip on deals for Cokers.

The points about tire pressure and suspension are very true. In my case, one of the front coils is sagging about 2" already, so there'll be suspension work to come, anyway. But that doesn't mean I want to break anything by running sky-high tire pressure.

Basically I'm just ending the period of "shakedown" (to see how much falls off or breaks when I push it) and am entering the period known as "sorting the car out." Driveability, tuning, and all that fun stuff. It really is fun, too. Although it's hard to beat a shakedown cruise, especially when you don't break anything! (That I know of yet).