Wheels and Tires Sponsored by Tire Rack
Click Here

Correct tire pressure?

Thread Tools
 
Search this Thread
 
Old August 16th, 2020, 04:52 PM
  #1  
Registered User
Thread Starter
 
harpelt's Avatar
 
Join Date: Jul 2013
Posts: 38
Correct tire pressure?

Hi Guys,

I just put on a re-painted set of ‘69 15X7 SSIII wheels with Cooper Cobra Radial 245/60R-15 tires on my ‘68 Cutlass. I have a slow leak in one tire, so I have to get that fixed, but when I was checking the pressure of the other 3 tires they were all over the place. I looked at my service manual and it says the proper pressure is 24 PSI but that seems pretty low. The tire itself says that the max pressure is 44 PSI. What is the correct pressure?

harpelt is offline  
Old August 16th, 2020, 05:04 PM
  #2  
Registered User
 
Fun71's Avatar
 
Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 13,879
The pressue decal in the car is for tire styles available in 1969, not modern radial tires.

The pressure on the tire sidewall is the maximun pressure at the maximum load rating.

So in reality modern radial tires on your car should be inflated to somewhere in the 30-36 psi range. I have similar tires and run them at 35 psi.


FYI, there were no 15x7 SSIII wheels in 1969. They may be 74-77 wheels.

Last edited by Fun71; August 16th, 2020 at 05:07 PM.
Fun71 is offline  
Old August 16th, 2020, 05:51 PM
  #3  
Running On Empty
 
Vintage Chief's Avatar
 
Join Date: Jul 2018
Location: Earth
Posts: 18,268
Originally Posted by Fun71
The pressue decal in the car is for tire styles available in 1969, not modern radial tires.
The pressure on the tire sidewall is the maximun pressure at the maximum load rating.
So in reality modern radial tires on your car should be inflated to somewhere in the 30-36 psi range. I have similar tires and run them at 35 psi.
FYI, there were no 15x7 SSIII wheels in 1969. They may be 74-77 wheels.
x2
Vintage Chief is offline  
Old August 16th, 2020, 10:55 PM
  #4  
Registered User
 
Ozzie's Avatar
 
Join Date: May 2009
Location: S.E. Louisiana, so far still in U.S.A.
Posts: 1,613
Try to get a reasonably accurate gauge. I try to keep mine between 30 & 35 PSI.
Ozzie is offline  
Old August 17th, 2020, 04:19 AM
  #5  
Frank Ignachuck
 
ignachuck's Avatar
 
Join Date: Jan 2012
Location: Maynard, Massachusetts
Posts: 1,288
I agree. Mine are at 32
ignachuck is offline  
Old August 17th, 2020, 07:07 AM
  #6  
Rocket Renegade!
 
BangScreech4-4-2's Avatar
 
Join Date: Dec 2014
Location: Vancouver Island
Posts: 4,465
33-35 here.
BangScreech4-4-2 is offline  
Old August 17th, 2020, 07:27 AM
  #7  
Old School Olds
 
tru-blue 442's Avatar
 
Join Date: Nov 2008
Location: Marble Falls TX
Posts: 8,949
35 psi here too.
tru-blue 442 is offline  
Old August 17th, 2020, 07:28 AM
  #8  
Registered User
 
jaunty75's Avatar
 
Join Date: Jun 2009
Location: southeastern Michigan
Posts: 14,213
I keep mine at 32.4432 + or - 0.0003
jaunty75 is offline  
Old August 17th, 2020, 04:00 PM
  #9  
Registered User
 
Fun71's Avatar
 
Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 13,879
Originally Posted by jaunty75
I keep mine at 32.4432 + or - 0.0003
I'm guessing that is with a mechanical gauge that reads from 0-200 psi and you are scrutinizing the hash marks on the stick.
Fun71 is offline  
Old August 17th, 2020, 04:34 PM
  #10  
Registered User
 
jaunty75's Avatar
 
Join Date: Jun 2009
Location: southeastern Michigan
Posts: 14,213
Originally Posted by Fun71
I'm guessing that is with a mechanical gauge that reads from 0-200 psi and you are scrutinizing the hash marks on the stick.
Pretty much.

What I do is interpolate between the spaced-one-micron-apart “32" mark and “33" mark on the fits-in-your-shirt-pocket 0-500 psi pressure gauge I bought with my paper-route earnings two-for-39 cents (I gave one to my Dad) out of the markdown bin at Key Drug Store in Rochester, New York in 1968. That drug store chain went out of business (or was bought out by CVS or something) in the 1980s, but I still have the gauge!



Last edited by jaunty75; August 17th, 2020 at 04:38 PM.
jaunty75 is offline  
Old August 17th, 2020, 04:49 PM
  #11  
Registered User
 
OLDSter Ralph's Avatar
 
Join Date: Sep 2017
Location: St. Paul Minnesota
Posts: 4,051
Originally Posted by jaunty75


I still use one !!!!!!!! Kids can't figure out how to turn it on or where the digital readout is.
OLDSter Ralph is offline  
Old August 17th, 2020, 08:19 PM
  #12  
Registered User
 
Fun71's Avatar
 
Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 13,879
One? I have a half dozen or so and that is the only style in my tool box and vehicles, although I have different ones such as 0-50, 0-100, 0-150 and 1, 2 and 5 psi increments.
Fun71 is offline  
Old August 17th, 2020, 08:53 PM
  #13  
Registered User
 
OLDSter Ralph's Avatar
 
Join Date: Sep 2017
Location: St. Paul Minnesota
Posts: 4,051
Probably two I can be sure of. One is kept in the console of my W-30. I'll have to look around to see if any are for sale now. I thought I was the only one that still used them.
OLDSter Ralph is offline  
Old August 17th, 2020, 09:38 PM
  #14  
Administrator
 
oldcutlass's Avatar
 
Join Date: Oct 2009
Location: Poteau, Ok
Posts: 40,624
Originally Posted by Fun71
One? I have a half dozen or so and that is the only style in my tool box and vehicles, although I have different ones such as 0-50, 0-100, 0-150 and 1, 2 and 5 psi increments.
Same here, you tend to collect them over the years. I run 35# in my Coopers.
oldcutlass is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
olds89
Ninety-Eight
7
April 4th, 2019 06:56 PM
Al Graaf
General Discussion
13
September 12th, 2012 08:20 AM
CO53Super88
Wheels and Tires
9
August 27th, 2012 08:28 PM
jdana24
Wheels and Tires
7
August 14th, 2011 11:05 AM
Doug69Cutlass
General Discussion
3
April 6th, 2009 06:54 PM



Quick Reply: Correct tire pressure?



All times are GMT -7. The time now is 12:34 AM.