1956 60S Tire Pressure

[Jerseycaddy56]

On my 56 Fleetwood 60S, the noted tire air pressure in the owner's manual and shop manual is 24psi, front and rear. I have bias ply BF Goodridge tires reproduced by a nationally known tire vendor to the classic world. I have been told the pressure is not correct for the reproduction tires and should be 32 to 35psi as this is the max. pressure indicated on the tire.

Any input would be appreciated.

[Roger Zimmermann]

When my '56 Biarritz was equipped with 8.20-15 tires, I had a tire pressure between 29 and 30 psi. To my taste, 24 is too low but 32 to 35 too high.

[Lexi]

When my '56 Biarritz was equipped with 8.20-15 tires, I had a tire pressure between 29 and 30 psi. To my taste, 24 is too low but 32 to 35 too high.

As usual Roger is correct. My '56 has 8.20 x 15 Coker bias ply tires and found that 30 psi works best, in my opinion. I tried 32+ but concluded that was a touch high. So 30 psi it is. Clay/Lexi

Note: When I park my car for winter storage I increase the pressure to 40 psi. Said to fight against flat spots when parked for 6 months. But car not driven at that pressure, just parked.

[35-709]

Usually it is the change from bias-ply to radials that requires a higher pressure, maybe whoever said that was thinking radials when the word reproduction was used.  Even so, 24 psi is kind of low but what was called for with bias-plies back then, bumping it up won't hurt.

[Lexi]

Agree. Makes sense. Clay/Lexi

[Jon S]

29 - 30 lbs for bias ply; 34 - 35 for radials works best. My dad used to tell me they recommended 24 pounds in bias ply tires as the car would ride smoother but also so that you would have to replace your tires that much sooner.

[5390john]

I have 235-75-R15 Goodyears on my '55 CDV. I find that 34 LBS is a pretty good pressure for ride/handling.
24 is definitely too low.
John Adams

[64\/54Cadillacking]

On my '64 Cad, I actually have bias-ply L-78 WW tires and I run 26 psi.

Bias-ply tires will always run at a lower pressure than Radials. I do believe 24 psi is too low, but I think Cadillac back in the day especially how the suspensions were originally designed, were made to use Bias-plys and oil filled shocks for the ultimate riding comfort.

I remember I had Radial tires on my '64 years ago, and it rode very rough but handled like it was on rails. I then slapped the proper Bias-plys on it and it instantly rode like a cloud but has sloppy handling.

[Caddy Wizard]

As others have said, for bias ply tires, 28-30psi is best.  Lower (24-26psi) will give a softer ride, but with more tire wear.  Bias ply tires give a good smooth ride, as the suspension was designed with bias ply tires in mind.

For radials, higher pressures work best, but make the ride a little harsher.  I run Diamondback radials on my 55 60S (the tires that look like bias ply tires, but are actually radials).  I typically run them at 36psi, but the ride is a tad harsher than I prefer.  So I might lower it to 32-34 psi.

[Jay Friedman]

I have 8.20-15 bias plies on my '49 and have always run with 25 psi.  From what I've read here I should increase the pressure to 28-30 psi.

[Michael Petti]

I worked in a full service station in mid 60ies. All bias ply tires. Many Cadillacs. 28 lbs standard pressure.  26 lbs softer and 30 for more mpg. 24 too low. Radials should be 32. 30 lbs for comfort. 34 pretty rough.

[James Landi]

"... I think Cadillac back in the day especially how the suspensions were originally designed, were made to use Bias-plys and oil filled shocks for the ultimate riding comfort."

Back in the mid-60's, I ran my '56 with bias at the recommended 24#'s.  By the early 70's, after switching to radials, I was very distressed by the harshness of the ride at 32#'s and over time, I kept "de-pressurizing."  Being aware of concerns regarding additional heat and possible tread separation, I'd keep the 24 psi for intown driving and inflate for highway driving.  When I was commuting 90 miles a day to work in my '67 Eldorado, I decided to keep the radials at the Cadillac recommendation--- I think it was 24 front and 22 rear, or something like that.  Doing so made a WORLD of difference in the ride and eliminated much of the harhness I attribute to the torsion bar suspension. My 1985 Biarritz convertible was designed to ride on radials at the 30 psi plus range, but even the standard Eldorado coupes were harsh if the radials were inflated over 30 psi.  James