I was at a local car show today and came across a 74 one owner C-3.  On the latch side of the drivers door this car had a tire pressure sticker that suggested 20 PSI for both front and back. The owner said this sticker came with the car when new.

Manufacturers suggest tire pressures for reasons such as smoother ride, traction, balance out the handling between front and rear of the car due to weight bias, etc. I've thought most manufacturers tend to recommend tire pressure unreasonable low for most cars. I don't know if that 20 psi recommendation is accurate or not, but it's way too low a setting as far as I'm concerned. I sold tires for years and would never recommend that.

I think a '74 vintage car would have come with tires rated at 32 psi maximum pressure cold. 20 psi would be so low as to create a lot of heat build up and wobble in the tire and excessive sidewall flex. I think the owner must buy a lot of tires due to premature wear on the outer edges if he keeps the pressure at 20 psi.

A more realistic pressure would be 30-32 psi...a bit harder ride, but improved wear, traction and fuel economy.

One of the problems Ford had with Firestone tire failures was due to heat buildup from unrealistic lower recommended tire pressures. There was some quality control issues with Firestones from one plany in particular, and this combined with low air pressures helped set the stage for rollovers.

Many if not most tires now are rated at least 35 psi maximum cold pressure, and many 44 psi or higher. I keep my tires inflated to the upper end of the rated pressure.

Nope...20psi was the factory rating, as stated on the door sticker, and the owner's manual. I've had my street tires and the original Firestones at this pressure from day one, with no problems. I have driven the '74 from Dallas to West Virginia once, and to the "Gathering" in PF, both trips with 20psi.
Granted, it rides really well, and would be harsher at 30/32psi, but, if Zora didn't have a problem with it, I sure don't.


                                                 clickAdams' Apple2006-10-15 19:00:09

[QUOTE=Adams' Apple]Nope...20psi was the factory rating, as stated on the door sticker, and the owner's manual. I've had my street tires and the original Firestones at this pressure from day one, with no problems. I have driven the '74 from Dallas to West Virginia once, and to the "Gathering" in PF, both trips with 20psi.
Granted, it rides really well, and would be harsher at 30/32psi, but, if Zora didn't have a problem with it, I sure don't.


                                                 click[/QUOTE]

If you feel you need to, go for it! I have run mine at higher pressures IF it is fully loaded with tools/Mama's clothes, etc., but it does effect the ride, and the tires will squeal a lot when rounding a fast corner. Like I said, I haven't had any problems at 20psi, but I can't state that you wouldn't. Contact BFG, and see what they say, before lowering your pressures.

Thanks for the suggestion Joel.

 I have 4 new BFGs on my 73. P255/60R15. BFG told me to run 24 PSI in front, 26 PSI in the rear. I run 28 PSI in all 4 tires. Tire pressure will go up a couple PSI when they are warmed up. I was a little worried about running 20 PSI in those big meats!

I don't git it...
These cars came from the factory with these pressure reccommendations, and were driven many a mile like that. True, the Firestone 500s had issues, but, that was a junk tire issue...not a pressure issue. I've heard of brand new 500s blowing on the Dealership showrooms.
I've put some hard & fast miles on the tires I have now at 20psi...no wear problems...no handling problems...and she rides really sweet!

I think the pressure on my '85 is 24 frt., 26 rear, on those huge steamrollers.

Keep in mind, larger tires can require less pressure than smaller ones.  And our cars have big tires.

'73s & up were radials...I'm not sure what the reccommended pressures were on the earlier(bias-ply) cars. Anyone wanna fill us in on that