My 1977 owners manual on page 5-17 says tire presure front 20 rear 26. Is that correct?

I looked at the sticker on the driver door of my '78.
it say
Max load 28 ft 32 rr
min load 20 ft 26 rr
never noted the minimum before.

Thanks for the quick reply Jeff.  What pressure do you run in your tires?

I run 28 to 30. 20 seems kind of low in the front. Maybe that is based on driver only and nothing in the back.  I would think it would ride more like a Cadillac at the lower PSI. Does your ZZ4 add extra weight compared to a stock 350?

If you look on the placard on the door, you will find the correct tire pressure recommendations. They may seem low by today's standards, but they are that way for a reason. That's the pressure that the car handles BEST(ie: safest) at. Never go by the numbers on the tire itself...those are Max pressures@temp.
The pressures on the door sticker are best for the car, depending on the load. More weight in the car(luggage, etc) would require more tire pressure.

This subject has been debated to death, since most folks just can't believe that GM would recommend such "low" tire pressures....
I run what Zora suggested....never had an issue at all. I do add a few pounds when loading it up for a trip, but never over 28psi front or rear. Gm spent millions of development dollars to determine these settings....I ain't smart enough to argue anything different.
Thass my story, and I'm stickin wid it....

OK, thanks guys, I just checked my tire pressure and all four of them was 34 psi.

Jeff, the zz4 has aluminum head, but its still close to a stock engine. It a good running enging.

I just checked mine the other day and set all four at 28. I think it rides and handles pretty good for a 31 year old car.

Kevin