L78-15 Tire Pressure

[55Bfred1752]

my recently purchased 1955 Buick Super Model 52 is equipped with L78-15 tires. What is the recommended tire pressure for these tires? 

 

[old-tank]

32 psi should work. 

But no matter what the pressure you will grow to hate those tires:  they are extremely rough riding and have the worst handling of any available tire.  The original size 760-15 will ride the best (best of the lot BFG Silvertown from Coker tire; harsher ride are the Coker Classic), but have typical bias ply handling (better than the flat top L78-15).  Diamond back radials are a good choice.

[Ted "Wildcat65" Nagel]

I was trying to see if there was a tire pressure decal somewhere.  I found one for 1954 that recommended 24 cold and 27 hot.

IMHO bias ply paradigm is lower pressure and will give better ride at recommended pressures.  

Corvair tire pressure for front was 15 psi.  Many handling problems with the corvair were from front tire pressure being too high.

I do like to increase pressure if in storage - my attempt at lowering chance of flat spots.

 

[C Carl]

I'm not 100% absolutely sure, but isn't that the size of the relatively new Diamondback Auburn radials.? Initial reports I have seen are enthusiastic. Bias look, radial advantages. Radial tires have a very large range of operating pressure, so may be tuned for conditions, speed, and ride. Safety first, if you actually drive your car.    -    Carl 

[NTX5467]

  You might check the tread width of the L78s.  See how much wider it is that the wheels on the car, which they are mounted on.  My suspicion is that the tire tread is wider than the rim.  With 32psi, that might make the tread "bow out" rather than be "flat", due to the narrower rim width.  Most cars which came with the L78s as OEM, usually had a rim width of 6".  

 

The orig tire size had a tread width that was close to the rim width, I believe?  In which case you could put higher pressure in them with no real issue other than better steering response and a rougher ride.

 

With bias-ply tires, it was common for the "soft ride" inflation to be 24psi.  Add 4psi if speeds over 60mph would be used.  That puts things at 28psi.  Then I'd add 2psi to the front to compensate for the front end of the car being heavier than the rear (with normal loads and passengers in the front seat only)--something I figured out for myself.

 

In the middle '50s, seems like I recall that the OEM inflation pressure of the "balloon tires" was around 20psi, many times?  There usually was more rubber in those tires, if that makes any difference.

 

Of course, all of the inflation pressures are set when the tires are cold, rather than "after use".

 

NTX5467 

Edited October 16, 2018 by NTX5467 (see edit history)

[55Bfred1752]

Many thanks for the response to my L78-15 tire pressure post. Apparently 32 psi is the recommended tire pressure for L78-15 tires. however, I plan to experiment with 30 psi, and perhaps 28 psi to see if the ride and handling is any better.

55Bfred1752

[NTX5467]

Handling is aided by higher pressure, ride inversely so.  30psi might be the best compromise.  

 

NTX5467

[RivNut]

Are these reproduction tires or originals.  If they're originals, you need to do some reading on the dangers of tires that are seven years old or older.  They're not safe for driiving.  But if you're only going to drive them on and off of a trailer, you might be okay.