Tire pressure?

Rusty Muffler

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My 57 Belvedere has new Hankook Optimo tires and KYB shocks. When driving it drives straight and firm except on coarse or weathered asphalt. I can really feel it in the steering wheel. It's great on smooth asphalt. Is that tire pressure or the nature of torsion bar suspension? The original recommendation for pressure is like 24 psi cold. But that was in 57. What should I be running these radials at? They're at 30 now.
 
Fill them up to 45 lbs. look at the max pressure on your new tires. The max press is not 32 like years ago, common is 51 psi max. So going by the 1957 air pressure sticker the 24 is only half filled.

Fill the tires and try it, it won't hurt the tire or your car.

I have a 1961 Chrysler with heavy options (AC, power seat, power windows, door locks, etc) and optimo tires. I had them at 37 psi and got edge wear on front tires. I fill them to 47 now and it feels better driving it.
 
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The Hankook Optimo 235/75-15 is not the best riding tire on my 64 C. I like them at 30.
Any small deviation didn't produce a lot of ride difference. But 40 was very hard ride.
 
These guys complaining about a hard ride, what is the condition of your shocks? Don't make the tire do the work of the shocks.
 
Max inflation pressure is not the spec. Follow spec or get a service manual that will have a chart with tire pressure specs.

Running max inflation is for seating beads. Running max pressure will result in a very hard ride, center tread wear, and can cause adverse handling characteristics that may effect vehicle control in an evasive maneuver.

That advice is dangerous and could put you or others in situation that may change life for ever.
 
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When the cars were designed and built, a smooth ride was the goal. I suspect that if you read the "full load" or "for speeds over 70mph" tire pressure recommendations, those pressure specs will be more like 30psi or even 32psi (which was the max pressure for normal 4-ply rated tires back then).

You also have to understand that road isolation was not nearly as good with the older bodies as it was in the middle 1960s bodies, for example. Or even the '63 bodies. Unibody cars never were the quietest cars on the planet, either, without large amounts of sound deadening in them. Think "undercoat" that might not be there any more, if it ever might have been. So look in the wheel wells and such, plus the underbody for undercoating of any kind.

Steel-belted tires are more prone to transfer road harshness into the body at around 45mph, being quieter at 55mph and higher. Something about the harmonics of the tires compared to bias-ply or belted-bias-ply tires. These things became apparent when radials were first sold in the middle 1960s, especially on some Chrysler products.

It is more the body structure and lack of sound and heat insulation (compared to modern cars) that make things sound noisier. First time I drove my grandmother's '58 Fairlane, it was louder inside than our '66 Newport, back then. Has little to nothing to do with the type of front-end suspension on the cars, but how extensively they were insulated.

In the short term, be more concerned about wind noise from aged weatherstrips. Plus the affect of aged body mounts on things, too.

So, keep the radials you now have. Start with 30psi frt/28psi rr and watch the tire wear. Especially with the narrow 5" rim width of the wheels used back then.

One possible fix to decrease the road noise is a "DynaMat" type underlayment for the floor. It can decrease noise transmission plus add some heat insulation, too. Shop for the best price as most of it is all the same stuff, although some might be thicker than others.

Glad the car is driving again!
CBODY67
 
Driving around at half the max pressure? That's what is dangerous for those around you. Take that 5000 pound car into a corner with 24-30 psi in the tires and watch how the tire is rolling over.
 
Driving around at half the max pressure? That's what is dangerous for those around you. Take that 5000 pound car into a corner with 24-30 psi in the tires and watch how the tire is rolling over.
That is hilarious! You are perpetuating misinformation about max inflation pressure.
 
A brand new 2024 Lincoln Nautilus with 33 PSI it weighs about 5000 lbs. The wheels and tires don’t come apart. There is sidewall flex on radial tires, it is nowhere near as bad as bias plys. My Imperials run 28 psi stock with bias plys and the cars were fine. You must have an engineering degree to speak with such authority. I don’t, but I do this for a living as a Ford-Lincoln tech.

IMG_0478.jpeg
 
That is hilarious! You are perpetuating misinformation about max inflation pressure.
You are keeping the sheep inline with those factory specs.

Fill your tires, it's free and you car will drive better. BE BRAVE, TRY IT. It won't crash or be unpredictable, that's what low tires do.

Why is the max pressure so high on a new tire? Why isn't it still 32?
The max press on those original tires was 32 psi:
so at 24psi that's 75 percent of max.
So on a tire with a 51 psi max, 75% that is 38 psi.

There is your apples to apples comparison.

Do you really think it is dangerous to drive around at 75% of the max press on the tire? Do you ever exceed the posted speed limit? That's endangering the public around you.

How about all these guys setting the front end for max caster and the offset bushings. That's not on the factory specs. Is that dangerous too? Better get some engineers involved in these front end alignment posts. That's FAR more dangerous that some added air in the tires.
 
You are keeping the sheep inline with those factory specs.

Fill your tires, it's free and you car will drive better. BE BRAVE, TRY IT. It won't crash or be unpredictable, that's what low tires do.

Why is the max pressure so high on a new tire? Why isn't it still 32?
The max press on those original tires was 32 psi:
so at 24psi that's 75 percent of max.
So on a tire with a 51 psi max, 75% that is 38 psi.

There is your apples to apples comparison.

Do you really think it is dangerous to drive around at 75% of the max press on the tire? Do you ever exceed the posted speed limit? That's endangering the public around you.

How about all these guys setting the front end for max caster and the offset bushings. That's not on the factory specs. Is that dangerous too? Better get some engineers involved in these front end alignment posts. That's FAR more dangerous that some added air in the tires.
I agree that people do dangerous stuff. You included. I run my Imperials at 34 psi per the engineer that wrote the chart and said it is OK. You are wildly off base and hope you only take yourself out when you get a blow out.
 
You must think of the entire vehicle, your 2024 Lincoln had many features and technology advantages your 72 Imperial doesn't have:

4 wheel independent suspension
Variable rate coil springs
Struts not shocks
Front and rear sway bars
Variable rate power steering
4 wheel antilock disc brakes
Electronic AWD
Traction control
Autonomous driving

And a coefficient of drag less than half of your old land barge car.

So your comparison is really out the window here.
 
And without my car there would be no 24 anything. Without any car from the past there would be no cars today. Technology builds are time goes on…progress. I see that you are scrambling to make this personal and you are now losing the argument. As a trained professional, this is hilarious, but as an individual who shares the road with you this is concerning that you are so set in your ways and stubborn.
 
I agree that people do dangerous stuff. You included. I run my Imperials at 34 psi per the engineer that wrote the chart and said it is OK. You are wildly off base and hope you only take yourself out when you get a blow out.
Sir you are now making foolish statements based on your fears. Your fears are showing here, how do you dare enter traffic?

How is the tire going to blow out at 75% of max pressure? The tire makes says 51 is the max pressure. I've driven tens of thousands of miles like this.

The car handles better TRY IT!

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And without my car there would be no 24 anything. Without any car from the past there would be no cars today. Technology builds are time goes on…progress. I see that you are scrambling to make this personal and you are now losing the argument. As a trained professional, this is hilarious, but as an individual who shares the road with you this is concerning that you are so set in your ways and stubborn.
You are so set in your ways you are afraid to add air to a tire and see how the car drives?
 
OK, you are right. Let's study history. Ford history.

Ford explorers tires blowing out and rolling over. Many lawsuits. Remember that? Remember the resolution?

They didn't have enough air in the tires, so they raised the tire inflation recommendations. Yes it's true read about it.

Firestone and Ford tire controversy - Wikipedia
 
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