I've been rooting around the interweb looking for some answers to the mysteries of tire pressure and thought "why not ask the pro's?" So, here it goes; what should I set my tire pressure to?

My truck is a 1964 F100 short bed with a hula girl dashboard dancer and a Johnson/Humphry bumpersticker. No "Recommended Tire Pressure" info on my drivers door.
The tires are just a few months old and are Hankook Optimo H724 P235/75/R15. 50 Max PSI

I currently have them at 42 PSI and it's like I installed power steering! I'm far from being made of money however so I'm more interested in what'll make these new tires last the longest. Lord knows my Popeye arms could use some manual steering workouts (and maybe a can of spinich)!

 

Your tires might not be designed or built to operate at pressure that high. If they are passenger car tires, about 32 is the limit, although some newer tires are used at 35. I use the same size as you, and the reason I changed from 255 TA's was to get more manageable steering. However, my tires are 10pr truck tires that my tire guy said are fine at 45 psi.
Maybe ask the manufacturer.
Eric

 

Do you have your 1964 Operator's Manual? The recommended tire pressures should be listed in there. The Operator's Manual was originally stored in the glove compartment.

Specifications begin on page 57.

1964 Ford Truck 1st Edition Operators Manual F-100 To 350 Pickup Gas and Diesel | eBay

That was for bias-ply tires, though.

But, anything over 32 lbs and below 50 lbs should be fine depending on load. What you have them set to sounds great. Watch the tread wear and if it is wearing in the center then reduce the pressure some.

.

 

64rednwhite Tires are much different than from 1964, so while others might, I suggest not to go to the manual and look at very outdated reading.

My O, you should be good at 35psi, what I run in everything.




John

 

Keep an eye on your tires. If they wear faster on the outside corners then add some air. If they wear faster in the middle then let out some air. If you plan to haul a load then pump up the tires to their safe limit.

 

He was looking for the inflation information on his door jamb like new vehicles have, but that would be just as dated. I was letting him know where to find the inflation information that Ford provided. Then I said that was for bias-ply tires so hopefully that was understood to be taken relative to when it was given by Ford.

I can run up to 70 PSI in the tires on my truck. They recommend at least 60 PSI. It really varies by the tire. To just say 35 PSI cause that's what you use is not a good recommendation for all.

I looked up the specs of his tire and then gave a range of pressures that are valid for it.

Chad

.

 

I run 80 in the front and 100 in the back on my pizza cutters in the winter when I normally have a ton or two of hay on the back.

 

What '65ford said.
Since they aren't the original tires and they probably aren't the original size, the spec is a good starting point but that is it. Do what the tires indicate that you need to do. When you find the pressure that works, write it down.

 

Sorry to resurrect a LONG dead post, but I'd love to hear how you like these tires now that three years has passed. I'm about to put my '70 F100 back on the road, and I'm contemplating buying these exact same tires for it. I Googled Optimo H724 F100 and found this post. LOL

 

Technically it should be pointed out, original bias-ply tire equipped trucks had wheels that are not necessarily designed to handle the greater sidewall flex of radial tires. So they say, fwiw.

I too have found it's better to inflate the front tires a bit more than the '64 spec if retaining the manual steering running radials. Don't get carried away, overinflation beats the hell out of wheel bearings.

 

Very interested too. Glad you brought it back up
My own experience has changed a lot since I started testing for my own unique pressures for each combination. And actually started rotating the tires too!

Naturally every vehicle and tire combination are different, depending on alignment and loading and such, but on every vehicle I've owned I do a quick-test rather than wait for tire wear to show me which way to go.
The tire wear scenario is basically the same, but I speed things up by using what we call the "chalk test" but I usually just use the dirt they get on them as an indicator.

It's really easy for the rear tires with their solid axle and relatively flat stance on the ground, but the front tires can be finicky on I-beam and similar setups where static camber is sometimes more notable.
But the basic premise is to wipe a bunch of chalk, or even just a thick single line of chalk, across the tread of the tire. Drive it a short distance on smooth pavement (whatever works, but 50 yards should do the trick) and note where the chalk has worn off.
As the others have said, if the chalk wears off only in the middle, reduce the pressure. If it wears out all the way to the edges then add some pressure. For passenger cars I get the rears to wear right out to the edge, but for trucks I usually put extra air in so the chalk will remain about 1/4" or so from the edge of the tread. To allow for additional loading at a moment's notice. For heavier loads you would add some pressure if going any distance at higher speed.
Of course a more square profile tire might act slightly different from a more rounded one, but the results are still usable and predictable.

With the fronts, a LOT depends on how it's aligned, but if the tires are sitting even just barely flat on the ground you can still make a reasonable estimate of what pressures are good.
And in the same vein as the chalk, just driving around if you occasionally glance at the tires to see where the dirt is remaining and where it has been cleaned off the tread by driving, you can do the same thing. For instant gratification though, the chalk method works great.
Aside from just the wear pattern you certainly need to consult the manufacturer if your running an extreme setup. That might be using tires rated at 2550lbs per, on a vehicle that only weighs 3,400 lbs total. In that scenario you might not be able to get even tread wear all the way across without deflating it to such a level as might be considered too much. Such as running a 75psi rated (maximum) tire at 22 psi due to the light weight of the vehicle.
I don't know of anyone having a problem from doing that, as those tires are also very heavy duty, but there is always a good reason to not go too low if your vehicle sees high speed use.

For examples, my F350 runs 60psi front and 40psi rear (when unloaded, which is most of the time) on E-rated tires with a 75psi max. My '71 Bronco runs 30frt and 25rr on C-rated tires with a max of 32psi. My '68 Bronco runs 32frt and 25rr on D-rated tires with a 50psi max. My '19 Chevy 1500 runs 40 and 30 where 44psi is max. Even my Buick Regal, which has a recommended pressure of something like 32psi front and rear has been changed. I run 40frt and 28rear on 45psi max tires. Some I've run have been fairly close to factory recommendations, while others have been way different.

As far as results, mileage-wise from a strictly tread wear standpoint I can get about 90k to 100k miles from a set of tires, car or truck. IFS trucks last longer, but pretty good with solid axle trucks so far too.
That's an estimate (but a pretty accurate one I believe) because I typically change my tires now from old age, rather than when the tread wears out.
And rather than just pressures, the tread wear I get is probably 80% due to regular rotation because the back half of all my vehicles hardly wears at all.

Paul

 

One thing to remember, original wheels were not designed for radials, as they didn't exist. Over the years I have seen (3) Ford, (1) Dodge, and (2) Chevy wheels that suffered rim cracks on rear wheels. All were overloaded (in my opinion), and running radials. All were 1960's trucks, on the original wheels. A Ford service manager told me that the wheels from the mid 70's vehicles on were heavier, and stronger. These were designed for the extra force exerted by radial tires. In the case of Ford wheels, he told me that the wheels with riveted in centers were the old style, welded in centers were the new style.

This is a job for..... NumberDummy!

Numberdummy, can you weigh in on this issue? If anyone will know, it will be you.

 

@NumberDummy hasn't logged in since early December of last year.

 

I thought he had been scarce lately.
I hope it’s just the Holiday Season that has him off line.

 

Here too. There are a couple of threads started just to thank him for his previous help, and to bring up the subject of his absence.

Paul