I believe I replied to a thread a while back RE tire pressure vs rough ride, maybe not. I am running 225/70 R19.5s on the front of Blue at 40 psi. I am running LT235/85R16s dual on the rear at 35 psi. I painted with white spray paint across the width of the tread, drove the truck and found the front to be wearing even across the tread. On the rears, I am riding on the center three ribs only at 35 psi and no where near "kissing".
I am tempted to try even lower front and rear and see what results are. BTW, if those duals "kiss" occasionally, it is not the death of the tires. Now, if you were carrying heavy loads, a constant "kiss" could cause overheating, wear on the sidewalls, all bad. My tires do not run hot. And I think I mentioned that I am running shocks on the front. And like Stu mentioned, rock crawlers run even lower. I've run oversize Jeep tires down in the low teens while playing in sand.
I realize they're running special tires, but I've read the NASCAR boys run pressures in the teens on the front inside at some tracks .
I would estimate that I've put close to 2000 miles on Blue running the above mentioned pressures. This included a trip to TS14 in OH and a bit of interstate travel.
The ride is still rough, it is a truck, but not the bone jarring ride you get running high pressures. I find the ride and handling very acceptable, a pleasure to drive. In fact, I drove Blue about 80 miles round trip to breakfast this morning.

 

Exactly what I was looking for. Thanks guys. (and thanks again Ray. I now remember you already answered this.)

Mike, I learned more from those two links than I thought possible. And I went searching online for some minimums, to no avail. And after reading these common sense responses, I feel pretty dumb for not thinking of looking online for some info before I asked the question. I really don't know why that is. I guess I expect current data are always for newer vehicles. But really, the tire pressure info applies to the tires I have now, since they're not the stock 7.00x18s that came on it.

The Shop Manual specs my truck front axle at 1,850 pounds on the stock 7.00x18 tires at 55 psi and 625 rpm, which I calculated to a little over 60mph HA HA HA! But I can't find any ratings for minimum pressure for modern radials. My SWAG is the front end probably weighs 3,000 pounds, so 1,500 pounds per tire.

So using Mike's second link and others I've since found online, I only see minimum inflation for my tire sizes at 65 psi for the front (2,410 lbs) and 70 psi for the duals (2,720 lbs).

Using Ray's experience with Blue, I'm going to leave the front at 40 psi and drop the rear to 35 or maybe 30. In her current configuration, Betsy will never see 60 mph unless she goes off a cliff. And I drive her less than 100 miles per month, so I doubt I'd notice any wear problems any time soon. The rear tires are almost new. If I ever do a rear end swap to a Dana70 for highway speeds, I'll be refurbing the rear springs at the same time and may accomplish less bounce then.

I thank you all again for getting my brain waves working again.

 

Ray, I went back through this thread to see what was recommended when I first asked the question about tire pressure. I know my memory of how I had the psi set proved to be inaccurate. But I don't remember seeing the actual reference to the correct lowered psi until today.

In post # 1151 you suggested playing with the tire pressure to slightly improve the ride. And you mentioned it again in post #1435, but again no specific psi. I responded with a lie, saying I had all the tires set to 40 psi. Again the big DUH!

And then I found it. Post #1430 is where you told me everything I need to know about tire pressure. 40 psi in the front and 35 psi in the rear. "When I reduced the pressures in the tires it got rid of the bone jarring rough ride." And 3 posts later, I thanked you for the information. Then I obviously did nothing about it... Next weekend, I'm going to lower the rears to 35 psi and take her for a drive.

Thanks again Ray.

 

Joe,
Your last post makes me feel better. I have done the exact same thing. Shoot, it was Ray then too that told me everything I needed to know, but I didn't get it until I reread some of the posts and found it again.

I'm not alone, thank goodness.
Be sure to let us know how the ride goes.

 

Yeah Joe, I seem to be talking (writing) too much and not listening (reading) enough. As the old saying goes, "You have two ears and one mouth, so listen more than you talk." Well, that's paraphrased... So in the case of the written word, it's two eyes...

And you know I'll update the thread after I lower the rear tire pressure. I can't keep my "mouth" shut.

 

So as if to prove my last statement, here's a bit of worthless trivia to add.

Back in post #1268 on April 5, I mentioned that I just turned over 26,000 on the odometer. Yesterday on my test drive, I turned over 26,100. So I'm only driving Betsy 20 to 25 miles a month.

This is partly because of her 2/35 air conditioning in 100+ temps this summer. But I really do need to get her out more often.

But I'm retiring in 43 days, so maybe I'll find the time to drive her more often...

 

41 days. Just saying.

 

Yes, I must be the infamous who's everyone asks about.

As in "But who's counting?" My countdown app tells me I have 1 month, 9 days, 11 hours and 3 minutes to go.

But that's not the real story. While I have 40 days to go, only 28 of those are work days. And since I still have one holiday and 2 weeks of vacation in that time, I'm actually down to only 17 days left to go to work.

But, who's counting?

 

Just got home from Denver today. I was going to lower the tire pressure on Betsy tomorrow, but I couldn't wait.

So I set the front and rear to 35 psi. I couldn't see any difference in the side walls so I think they'll be fine with no weight on the truck.

Then I figured she needed a real test. Because I wanted an unbiased opinion (and I know I wanted to believe this was actually making a difference) I asked my unbiased, yet experienced Betsy passenger wife to go for a test ride with me. No pics or video, sorry.

We drove around on a few streets that normally test the seat belt tensile strength. SUCCESS!!!

Yes, Betsy still rides like a truck. A very bouncy truck. But the jolting has stopped. It was actually a pleasant drive. She said "This is nice".

You may remember that 3 months ago, while tightening the bolts on the flatbed which apparently had loosened because the wood shrank, I smashed and split open my finger tip and had to quit working on the truck. I realized today that I had never finished that job, and so I did it before the drive. Only about half of the nuts were loose.

Thanks again to all who offered advice on my jolting ride. FTE rocks!

And especially thanks to Ray, who shared his real world experience with his F4.

 

Congratulations! I was thinking tonight, I can't wait until I can just take my truck out for a drive. Shoot, this evening after grinding rust for 2 hours, I just sat in the truck and started her up and sat in it with the engine running for a minute. Your smoother ride will make your jaunts just that much nicer.

 

Thanks. I hope you're driving yours real soon.

I was already thinking about errands I might be able to drive Betsy on tomorrow...

 

Great news, driving them is what it is all about.

Now you just need to install an auxiliary transmission so she is more comfortable on the road.

 

I've considered that. You mean like a Brownie Box, right? I think part of this huge thread is devoted to that subject. I'll have to go back through it again since my memory isn't what it used to be.

 

Why don't you remove some of the spring leaves? Whith what u are doing with Betsy, u don't need those heavy springs.

 

Yes, that's been discussed before. I will never load her up to use the overload springs and probably could do without some of the others as well. I certainly don't intend to ever have the 5,000 pound payload she was built to handle.

But Betsy is an F4, and I have no intention of lowering the height. I like climbing up into the cab. She sits higher than, or at least as high as, a lot of the lifted newer 4x4s passing me on the street. I say passing me because I'm always the slowest vehicle around.

One day after I retire, I may get around to removing all four sets of leaf springs and refurbishing them. But I'm not looking forward to that job. When I do that, it will most likely be because I have decided to swap the stock Ford 5.14:1 rear end for a Dana 70 so I can have higher top end speed. It would then make sense to overhaul the suspension since it will have to come out anyway. That would probably include a transmission change as well. But since I know of no swap for the F4 front end which has no shocks and a straight axle, I'm not in a hurry to do any of that. And that job may very well be beyond my skill level.

I am still getting used to the bounce instead of jolt after lowering the tire pressure. I don't want or expect Betsy to ride like an F1 or a newer truck. If I wanted that kind of ride, I'd buy a different truck.