What Tire Pressure ?
Thread Starter
Racer
Joined: Feb 2004
Posts: 321
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From: Murrells Inlet SC
What Tire Pressure ?
What do you guys recommend as a tire pressure for normal street/cruise use? I have a 72 Convertible with an LS-5 and 4-Spd. I recently installed Fireston Firehawks Indy 500 tires, 235/60/15 front and 255/60/15 rear. I am running 32 psi in them but don't know what the optimum pressure is for good traction and uniform wear. What is your suggestion? :confused: :confused: :confused:
Melting Slicks
Joined: Jul 2002
Posts: 3,000
Likes: 22
From: Boulder Creek California
Re: What Tire Pressure ? (gh78)
my door says 20/26.. mmm... don't think so. Really, you have to figure out what your contact patch is, as it will vary with car weight.
I have a question... what effect do tire sizes have on the necessary pressure?
I have a question... what effect do tire sizes have on the necessary pressure?
Thread Starter
Racer
Joined: Feb 2004
Posts: 321
Likes: 0
From: Murrells Inlet SC
Re: What Tire Pressure ? (MEAN72)
I got the number for Bridgestone/Firestone Technical Support Services (1-800-847-3272) and asked them 'what tire pressure?'. They were very polite and courteous but the best information I could get was a load vs. pressure table which they Faxed to me. I contacted Tire Reack and they told me I should run the recommended pressure for the car. My 32 year old car came equiped with F70-15 tires. My car placard and owners manual tells me to use 24 psi (cold) pressure in my tires. This seems way to low to me for modern tire design and oversized tires. Tire Rack tells me the prressure is based upon the car, not the tires. I believe this within ceretain modern bounds but not for a 32 year old car and tire design. :confused: :confused: :confused: I am going to run 30 psi in the tires and see what happens unless you guys can tell me different. Thanks for your help. Any further suggestion guys? :confused: :confused: :confused:
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Thread Starter
Racer
Joined: Feb 2004
Posts: 321
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From: Murrells Inlet SC
Re: What Tire Pressure ? (RUXperienced)
"what effect do tire sizes have on the necessary pressure? "
Tire Rack says none, even though the sizes have changed the car has not. They say that the air pressure is based on the vehicle and that we should still run the recommended air pressure for the car.
I am not a believer. I wouild think that 32 years of tire design changes would change the footprint to pressure ratio.
:confused:
[Modified by MEAN72, 3:42 AM 2/26/2004]
Tire Rack says none, even though the sizes have changed the car has not. They say that the air pressure is based on the vehicle and that we should still run the recommended air pressure for the car.
I am not a believer. I wouild think that 32 years of tire design changes would change the footprint to pressure ratio.
:confused:
[Modified by MEAN72, 3:42 AM 2/26/2004]
Racer
Joined: Oct 2000
Posts: 405
Likes: 31
From: Houston, Texas
Re: What Tire Pressure ? (MEAN72)
I have BFG Radial TA's 245 15 60s all around on my 72 small block, and found that 30-31 in the rear and 28 in the front was the best combination. 30 in the front made the car bounce a bit too much for my driving; which is just cruising with a little screech now and then.
Hope this helps.
Hope this helps.
Drifting
Joined: Feb 2002
Posts: 1,906
Likes: 0
From: Berlin
Re: What Tire Pressure ? (MEAN72)
There are a lot of factors that go into the OEM pressure recomendations, and it does have a lot to do with the specific tire on the car. Besides tire wear, the pressure also affects the various traction characteristics of the tires and also changes the ride. If you want performance, you should try different pressures, and see what you like. It can really change the feel of the car, and isn't dangerous unless you're really careless about it.
There's no possible table that will be anything more than a starting point. There's a lot of personal preference involved, as well as your specific alignment and suspension setup (and weight distribution of course).
There's no possible table that will be anything more than a starting point. There's a lot of personal preference involved, as well as your specific alignment and suspension setup (and weight distribution of course).
Drifting
Joined: Nov 2000
Posts: 1,536
Likes: 10
From: Sault Ste Marie Ontario
Re: What Tire Pressure ? (MEAN72)
Your tire pressure will depend on what your are trying to obtain with your car. If you are looking for best gas mileage and tire wear you should be running between 32 and 35psi as suggested on the tire. :blueangel:
If you run very low tire pressure you stand the chance of blowing a tire at highway speed on a hot day. :cry If you are looking for traction you should go to a abandoned lot and do a burnout and check for tire patch on the ground and then adjust until the patch is of even color and size (width) :D
I would suggest something between traction and reliability in the 30-32 psi range :thumbs: My $0.02 Personally I run 26 left side rear 28 right side rear and 29 in the two fronts. This give me best traction as well as with the staggered pressure my car takes of straight and the rear does not skate out to the right. :cool: If I run the highway to a car show I up the pressure all the way around to 34 psi. ;)
If you run very low tire pressure you stand the chance of blowing a tire at highway speed on a hot day. :cry If you are looking for traction you should go to a abandoned lot and do a burnout and check for tire patch on the ground and then adjust until the patch is of even color and size (width) :D
I would suggest something between traction and reliability in the 30-32 psi range :thumbs: My $0.02 Personally I run 26 left side rear 28 right side rear and 29 in the two fronts. This give me best traction as well as with the staggered pressure my car takes of straight and the rear does not skate out to the right. :cool: If I run the highway to a car show I up the pressure all the way around to 34 psi. ;)
Race Director
Joined: Sep 2002
Posts: 10,362
Likes: 5
From: San Diego - Deep Within The State of CONFUSION!
Re: What Tire Pressure ? (MEAN72)
I'm running same tire - Indy 500 Firehawk but I have 255/60's all the way around. 35PSI is a bit of a harsh ride .... I run 32 all the way around at the moment.
Race Director
Joined: Sep 2002
Posts: 10,362
Likes: 5
From: San Diego - Deep Within The State of CONFUSION!
Re: What Tire Pressure ? (SanDiegoPaul)
The original recommendation for tires was based on Bias Ply rubber, not radials. That is the reason taht the pressure recommendation was so far off target.
:yesnod:
:yesnod:
Thread Starter
Racer
Joined: Feb 2004
Posts: 321
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From: Murrells Inlet SC
Re: What Tire Pressure ? (SanDiegoPaul)
I talked with Tire Rack this morning and Firestone yesterday. I gained no knowledge except that no one in the retail tire business understands that tire design has changed in 32 years when we went from the original equipment F70-15 bias ply tire to the 255/60/15 radial tire I am now running. Sure, the car is the same and pounds per square inch can still hold up so many pounds (if the area is same) but they fail to realize that the link in between that has changed is the tire itself. The tire structure is entirely different. The sidewalls are more flexible. The belts within the tire are different, etc, etc.
I know that my placard calling for 24 psi is not right. I would hatre to take a hard corneer at 24 psi or run susained high speeds. Maybe I will drop the pressure down to 28 psi but no further. :steering:
Thanks for your help and suggestions.
I know that my placard calling for 24 psi is not right. I would hatre to take a hard corneer at 24 psi or run susained high speeds. Maybe I will drop the pressure down to 28 psi but no further. :steering:
Thanks for your help and suggestions.
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
Re: What Tire Pressure ? (MEAN72)
For normal daily driving, ignore door stickers and other advise. For your safety and others, always use the tire pressures recommended and load ratings posted on the side of the tire. :cheers:
Instructor
Joined: Sep 2001
Posts: 201
Likes: 0
From: Holbrook NY
Re: What Tire Pressure ? (Fang S-289)
Mean72,
I am running the same size tires as you and I keep the pressure between 28-30lbs. I have about 20k on the tires, and they are wearing well. I find that any more air pressure than that makes my ride quality fall off.
I am running the same size tires as you and I keep the pressure between 28-30lbs. I have about 20k on the tires, and they are wearing well. I find that any more air pressure than that makes my ride quality fall off.
Thread Starter
Racer
Joined: Feb 2004
Posts: 321
Likes: 0
From: Murrells Inlet SC
Re: What Tire Pressure ? (Sleper)
...you should be running between 32 and 35psi as suggested on the tire.
The only pressures on my tires are a maximum presssure of 44 psi and a 40 psi maximum pressure for safety when mounting the tires. Neither is recommended for normal running, Is your pressure on the tire of 32 to 35 psi a maximum pressure or a recommended running pressure? :confused:
