Tire Pressures? - Pontiac GTO Forum
User Tag List

 
LinkBack Thread Tools Display Modes
post #1 of 9 (permalink) Old 04-04-2012, 07:57 PM Thread Starter
 
1968 Q8's Avatar
 
Join Date: Jun 2011
Location: Whitby, Ontario, Canada
Posts: 50
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Tire Pressures?

Hey team!

My 68 owners manual says 24 and 26 psi on the tires, seems a little low??? Was that recommended based on ride quality or was it based on the tire construction back then...?

215/70/14 BFG radial t/a are what i'm on, what's a good pressure to run for regular driving?

Thanks guys.
1968 Q8 is offline  
Sponsored Links
Advertisement
 
post #2 of 9 (permalink) Old 04-05-2012, 06:43 AM
Super Moderator
 
GTO JUDGE's Avatar
 
Join Date: May 2005
Location: Lancaster, PA
Posts: 8,433
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 19 Post(s)
Garage
Quote:
Originally Posted by 1968 Q8 View Post
Hey team!

My 68 owners manual says 24 and 26 psi on the tires, seems a little low??? Was that recommended based on ride quality or was it based on the tire construction back then...?

215/70/14 BFG radial t/a are what i'm on, what's a good pressure to run for regular driving?

Thanks guys.
Was that on bias-ply or radial? I keep it at 35psi on my 14" T/A's.

President: GTO Association of America
www.gtoaa.org


GTO JUDGE is offline  
post #3 of 9 (permalink) Old 04-05-2012, 07:19 AM
 
SANDU002's Avatar
 
Join Date: Oct 2004
Location: BROOKEVILLE, MD
Posts: 1,116
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
I run 32 psi on 225/60/15's


67 Post Coupe,
69 RA III Judge
06 BOM, M6, 18's
SANDU002 is offline  
 
post #4 of 9 (permalink) Old 04-05-2012, 08:14 AM
 
facn8me's Avatar
 
Join Date: Jul 2011
Location: Tulsa, Ok
Posts: 574
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Actual needed pressure will vary from car to car and tire to tire. Yes the pressures on your car was based on tire technology available when it was built. On the side of the tire will be max pressure and the weight it will handle. Just to put it into perspective. My wifes jeep has 285 75 16's on it. 1 tire will at 60 psi will handle the entire weight of her jeep. With all 4 tires at 60 psi the jeep is very close to undrivable. at 28 pounds in the tires the tire has a full contact patch has a decent ride. Same way on my big chevy. Run 34 pds in it for ride and tire wear. Too much air and you'll wear out the center. Too little and there goes the outside tread. A slightly dirty road and a lil trial and error will show up ground/tire contact. I wish there was some formula (and there probably is) to take weight of car tire load ratings and come up with a suitable air pressure for everybody. If you find it let me know.

https://www.gtoforum.com/signaturepics/sigpic18842_1.gif

1966 Pontiac Lemans Convertible
389 tri power
facn8me is offline  
post #5 of 9 (permalink) Old 04-05-2012, 09:25 AM
64-67 Expert
 
geeteeohguy's Avatar
 
Join Date: Feb 2008
Location: Fresno, California
Posts: 8,470
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 98 Post(s)
I agree.....and I worked for a tire company for 14 years. Disregard the glove box pressures unless you are running repop bias belted tires, and even then, the label is suspect. When I ran bias belted tires in my GTO's (they were still available everywhere) I ran the same pressures I run currently in my radials: 30-32 psi front, 32-34 psi rear, depending on the load and the type of driving. On long cross country hauls with a trunk full of gear, I go higher, into the low 40's.
geeteeohguy is online now  
post #6 of 9 (permalink) Old 04-05-2012, 10:31 AM
Super Moderator
 
BearGFR's Avatar
 
Join Date: Aug 2008
Location: Springtown, TX
Posts: 5,731
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 122 Post(s)
Garage
Best to follow the advice of the tire manufacturer / tire shop.

Bear

BearGFR
Springtown, TEXAS
BearGFR is offline  
post #7 of 9 (permalink) Old 04-05-2012, 01:18 PM
 
facn8me's Avatar
 
Join Date: Jul 2011
Location: Tulsa, Ok
Posts: 574
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Quote:
Originally Posted by BearGFR View Post
Best to follow the advice of the tire manufacturer / tire shop.

Bear
You must have better info than I do or the internet can provide and much better tire shops than around here. Seen many a low profile tire and wheel destroyed because some gave the advice of 32 pounds of air was fine. See many over inflated and underinflated many tires destroyed because jimbo making $9 an hours said the tire say's 80 psi that's what it takes. To many different tires that are different than the factory tires. Case in point. Here are the specs on two different tire. BOTH are 225 75 r15's One will hold 1764 lbs at 44 psi. The other will do 2475 lbs at 65 psi. Either one of those tires set at max pressure will be overinflated and way to rough. BUT either could have pressures played with and perform fine. In most cases manufatures recomendations are at a specific weight and pressure making sure the real world is nowhere in the picture. By taking these two tires below and they were random. Your vehicle would need to weigh min of 7046 lbs for the pressure to be correct.

600 A B 1764 lbs.
44 psi
11/32"
29 lbs. 6-7.5"
6.5"
9"
NA
27.4"
761




None 2470 lbs.
65 psi
12/32"
31 lbs. 6-7.5"
6.5"
9"
NA
27.4"
758

https://www.gtoforum.com/signaturepics/sigpic18842_1.gif

1966 Pontiac Lemans Convertible
389 tri power
facn8me is offline  
post #8 of 9 (permalink) Old 04-08-2012, 08:31 PM Thread Starter
 
1968 Q8's Avatar
 
Join Date: Jun 2011
Location: Whitby, Ontario, Canada
Posts: 50
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks for the responses guys!

Great info as always
1968 Q8 is offline  
post #9 of 9 (permalink) Old 04-24-2012, 02:00 AM
 
Join Date: Mar 2011
Location: Texas
Posts: 704
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
the two tire comparison for the same size is suspect. one of those tires is not to be used on a car. The max pressure on the sidewall is based on that tire being used on a vehicle close to design loads. On our cars, those suspensions were based on the original factory supplied tire. Even a switch to radial was not part of the design.
pontiac is offline  
Sponsored Links
Advertisement
 
Reply

  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO General Discussion

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Pontiac GTO Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
What size tire for a snow tire on my 04? BL3 Wheels and tires 5 11-26-2011 10:35 PM
Just got back from tire shop, 15x7 275/60/15 Max tire? HELP! GreenMachine 1964-1974 Tempest, LeMans & GTO Technical and Electrical Wiring 9 07-20-2010 05:33 PM
Yep...more tire rub.... hunter35 Drive train, suspension, alignment and brakes. 8 03-25-2007 07:32 PM
Tire pressures........... johnebgoode Wheels and tires 3 01-26-2006 11:57 AM
tire pressures PhantomGTO Service, Maintenance and Technical Discussion 8 08-25-2005 12:49 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome