Tire Pressure

#X#x 41 lbs of air in a radial! You could have saved a bunch of money and just bought a couple hockey pucks for tires. Tire pressure is a compromise between the weight of the car, the suspension of the car, the tire design and the driving characteristics you like to feel. The tire characteristics are controlled by the air pressure not enough builds up heat and casing wear, too much a harsh ride and odd tread wear. Since this isn't an overly heavy car a good starting point would be in the 30 lb pressure range and adjust it up or down in 2lb increments until you like the ride and the tire doesnot appear to look like it is going soft or flat which would be too low a setting.
 
Kube said:
I didn't figure you made it up :)
You say your car is stock... then how about filling the tires to what Ford recommended back in 1940? That was 30#.
When I buy tires for one of my modern cars, I don't ask the guy installing and / or selling them how many pounds - I look either in the owners manual or in most cases, the decal within the left door. THAT is the manufacturers specification for that particular vehicle.
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Ford didn't fit radials in 1940.
 
The air pressue recomended by the auto manufacture is not always the best pressure for the tire to hold up and wear right.It is like asking Firestone what valve setting to use on your flathead Ford. That makes just about as much sense. Marv
 
Marv said:
The air pressue recomended by the auto manufacture is not always the best pressure for the tire to hold up and wear right.It is like asking Firestone what valve setting to use on your flathead Ford. That makes just about as much sense. Marv
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With all due respect Marv, I feel your line of reasoning is a bit convoluted.
The tire manufactures build tires to the specifications of the auto manufacturer with of course proper consideration to the laws that govern the safety, etc. required by the government.
It is in fact the car manufacturer that tests what pressure is best for the vehicle in question.
I do agree with you that the recommend pressure (by the car manufacturer) may not allow the best wear characteristics but that was not the concern of the fellow that posted the initial thread on this subject.
Yes, of course different pressures will effect the longevity of the tire as well as the ride. Some folks will choose to sway from the car manufactures recommendation to add longevity to the tires and / or change the ride 'feel' to suit their personal taste.
The original question that started this post had to do with a stock '40 Ford. That person was questioning why his car seemed to be 'floating' at 41# PSI.
 
Since these early wheels are not designed for a radial tire, I think Coker is doing a CYA with the higher recommended air pressure. I have had no problems with my radials on '35 Ford wires using 32 psi. Ed
 
41ford1 said:
On my stock suspension pick up I am running 215/75R15 in front and 235/75R15 in the rear. All are set at 35 PSI. No abnormal behavior at all. Ride is good for an old pickup and it goes where it pointed.
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The difference in tire sizes will makea difference in the way car or truck steers
 
Kube the reason i made that statement was because Ford and Firestone had lawsuits because of i believe Ford Excursions and Lincoln Navigators. Ford recomended i think 28 lbs of air in the tires. This made them ride good but caused poor handling and caused tire failure. When you run low air prssure in a radial tire for very long it causes the wire to break and you have a blowout usualy. The different causes of floating that i know of is Improper front end alignment, To much air in tires, To wide of tire for the rim width. To light of vehickle for tire width, and The actual tread design. There could be more that i cannot remember. I hope this helps and is just my opinion. I was familiar with the tire business at one time. I did not mean any disrespect to anyone. Marv
 
Marv said:
Kube the reason i made that statement was because Ford and Firestone had lawsuits because of i believe Ford Excursions and Lincoln Navigators. Ford recomended i think 28 lbs of air in the tires. This made them ride good but caused poor handling and caused tire failure. When you run low air prssure in a radial tire for very long it causes the wire to break and you have a blowout usualy. The different causes of floating that i know of is Improper front end alignment, To much air in tires, To wide of tire for the rim width. To light of vehickle for tire width, and The actual tread design. There could be more that i cannot remember. I hope this helps and is just my opinion. I was familiar with the tire business at one time. I did not mean any disrespect to anyone. Marv
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Hey Marv,
I didn't feel any sense of disrespect.
You make some valid points for certain. I do vaguely recall the Excursion debacle.
 
01aford said:
Took them down to 35 psi. Drove much better.
Thanks
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Good job. This is what Goodyear has to say, taken directly from their web site:

"Proper inflation is the single most important part of tire care. The inflation pressure on the side of the tire is the MAXIMUM operating pressure. It is not necessarily the right inflation for your vehicle. Always use the inflation recommended by the vehicle manufacturer. You can find it in your owner's manual, posted on the edge of the driver's door, on a door post or on the inside of the glovebox door. Always check inflation when tires are COLD: when the vehicle has been driven less than a mile or one hour or more after driving. Use a good quality tire gauge. Note: It's natural for radial tires to have a slight bulge in the sidewall at their proper inflation pressure. Check or adjust inflation every few weeks, before any long trip or if traveling with a heavy load. And don't forget to check the spare. Your Goodyear retailer can answer any questions you may have about tire inflation."

Realizing you have no door label, it only makes sense that you use cars of a similar weight as a realistic guide.
 
It probably felt like it was floating because it was overinflated, causing a smaller contact patch, thus lower traction.
 
Manufacturers specs is fine and works on manufacturers spec tyres. Change the wheel and tyre spec and that specific recommendation goes out the window. Especially when comparing bias to radial.
 
The car manufacture is out to sell cars. They will have you running low air pressure for a good ride etc. You can not set any one specs for tire pressure on autos with different drivers. Someone that drives a particular car at 55mph all the time may be able to run the auto manufactures recomended air pressure. If a person wants to run the same auto at high speeds he may have to increase the airpressure so the car will handle properly at higher speeds. When i was young i came close to getting killed because the idiot mounting my tires did not put the airpessure that i told him to use, but instead used the door sticker pressures. Now i know you trust no one, no matter what your instructions are, check for yourself. I was young and did not, but lesson learned. Marv
 
I use36 psi in my coker radials on my 51 ford convertible the car runs stright and DOES NOT follow every grove in the road,BIG improvement over bias tires ,Bruce has a good plan. Harold central coast Ca.
 
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