Trying to soften the ride on my 2012 F 350 Quad Cab King Ranch SRW

[09 harley]

Originally Posted by smurfsofwar

It can, but use the chalk test to see how far you can go. You may be surprised. But you'll want to air them up or you will damage them when you're loaded.

I have no idea what the chalk test is but it can't be very accurate. Tires have a max pressure for their rated load. If you have half the load you don't need max pressure. It's really pretty simple. Go on the Toyo Tire website and check out their extensive tables showing recommended pressure for the actual weight on the axle. You need to weigh each axle and then use the tables to determine pressure. When you are unloaded you can air down to help the ride. Anyone who says you have to always run max pressure is mistaken. The pressure on the door jamb is put there to protect the companies. If they listed several pressures then if there was a problem they would be on the hook. We need to use common sense, which isn't so common today.
Please look at the Auto Flex website. I believe they are in Thunder Bay Canada but they have numerous dealers and installers in the US. They have an air bag setup that is much better than just adding air bags. They automatically maintain ride height.
I only know one person who has this system and he is impressed with the improvements. I have a new 2017 F250 on order and am considering adding it shortly after I get it. There are numerous videos on the setup and Fast Lane Trucks has some good ones.

[09 harley]

Originally Posted by maxjr758

Does lowering the psi, not damage the tire, or at least cause uneven wear ?

NO! That is an old wives tale.

[09 harley]

Originally Posted by Fishalaska1

Air pressure makes a difference empty, I run 65 psi on all 4.

Is the 65 psi just a figure you decided on arbitrarily or is it based on research done by a company that gives us the appropriate pressure for the load. Since your axles don't weigh the same then it follows that the tire pressure should be different not the same.
There are scientific methods used to recommend pressure and that is what I prefer to use.

[Fishalaska1]

Originally Posted by 09 harley

Is the 65 psi just a figure you decided on arbitrarily or is it based on research done by a company that gives us the appropriate pressure for the load. Since your axles don't weigh the same then it follows that the tire pressure should be different not the same.
There are scientific methods used to recommend pressure and that is what I prefer to use.

Wear patterns I observed on my particular tire brand.

[drittal]

Originally Posted by 09 harley

NO! That is an old wives tale.

An under inflated tire will wear uneven, cause excess heat that could lead to failure.

[smurfsofwar]

Originally Posted by 09 harley

I have no idea what the chalk test is but it can't be very accurate. Tires have a max pressure for their rated load. If you have half the load you don't need max pressure. It's really pretty simple. Go on the Toyo Tire website and check out their extensive tables showing recommended pressure for the actual weight on the axle. You need to weigh each axle and then use the tables to determine pressure. When you are unloaded you can air down to help the ride. Anyone who says you have to always run max pressure is mistaken. The pressure on the door jamb is put there to protect the companies. If they listed several pressures then if there was a problem they would be on the hook. We need to use common sense, which isn't so common today.
Please look at the Auto Flex website. I believe they are in Thunder Bay Canada but they have numerous dealers and installers in the US. They have an air bag setup that is much better than just adding air bags. They automatically maintain ride height.
I only know one person who has this system and he is impressed with the improvements. I have a new 2017 F250 on order and am considering adding it shortly after I get it. There are numerous videos on the setup and Fast Lane Trucks has some good ones.

It's surprisingly accurate to show you how much contact your tire is making on the road.

I have and do use pressure calculations. All the time. The chalk test gives you an idea of what surface contact your tire is making which is a quick way to tell whether the tire pressure you are running will cause accelerated uneven wear.

And as an aside- YES an under inflated tire can wear unevenly, can fail due to over heating and can cause undesirable handling characteristics. It is not an old wives tale. Hence- the chalk test (or something similar) it allows you to SEE the physical contact- where rubber meets road. Something all the charts in the world can't do. Nobody says you have to run max PSI but there certainly is a threshold that will cause poor wear characteristics.

Let's be clear that I am not disagreeing with you. I am however saying that there is more than one way to skin a cat, and just because there are other ideas out there they should not be immediately dismissed as wrong.

[Gordon Dewald]

If you take a tire and use the max weight and recommended minimum tire pressure you can calculate the contact area. Weight/pressure will be very close.

If you reduce the weight on the axle you can reduce the pressure to keep the same contact area. The tire charts should be close to keeping the same contact area. There are likely other issues like the stiffness of the sidewall and tire construction that will influence their numbers.

An underinflated tire will run hot and if run that way long enough will fail. An overinflated tire will give you a harsh ride, may cause skittish handling and will have a reduced contact area which could affect traction and braking.

[Fishalaska1]

Originally Posted by smurfsofwar

It's surprisingly accurate to show you how much contact your tire is making on the road.

I have and do use pressure calculations. All the time. The chalk test gives you an idea of what surface contact your tire is making which is a quick way to tell whether the tire pressure you are running will cause accelerated uneven wear.

And as an aside- YES an under inflated tire can wear unevenly, can fail due to over heating and can cause undesirable handling characteristics. It is not an old wives tale. Hence- the chalk test (or something similar) it allows you to SEE the physical contact- where rubber meets road. Something all the charts in the world can't do. Nobody says you have to run max PSI but there certainly is a threshold that will cause poor wear characteristics.

Let's be clear that I am not disagreeing with you. I am however saying that there is more than one way to skin a cat, and just because there are other ideas out there they should not be immediately dismissed as wrong.

Every tire make is different. I let the wear pattern tell me. I prefer to drive through water on my concrete driveway to show me the pattern.

[smurfsofwar]

Originally Posted by Fishalaska1

Every tire make is different. I let the wear pattern tell me. I prefer to drive through water on my concrete driveway to show me the pattern.

Exactly. That is the same. That works well too! Little water will leave an imprint and you get a good idea if you're making enough contact.

If I ran my BFGs at the same pressure as my Duratracs I got uneven wear on the outside edges. Same load rating but different wear. I used a streak of chalk on the tire to find the sweet spot.

[maxjr758]

Thanks for all the info. I understand " it's a truck", and a great one, to me anyway, just picking everyone's brain to see if anyone had come up with a solution to the buckboard syndrome!
Harley I saw a system simular to Auto Flex a few days ago, and thought I'd found the solution. A TR4 Airide system, but discovered, it was discontinued in 2014.
Due to budget constraints! I ordered a set of SumoSprings, and a set of rear BILSTEIN SHOCKS for the rear of my Bouncing Betty!
Couple these parts ànd the decreased tire pressure maybe it'll help ! I'll keep yall posted !
Thanks again !

[09 harley]

Originally Posted by Fishalaska1

Wear patterns I observed on my particular tire brand.

Rather than run your tires long enough to see a change in wear pattern, which could take quite a few miles, it makes sense to use what experts say is the correct pressure for the load being carried. Of course you are free to do whatever you want it would just seem that using the correct info makes sense.

[09 harley]

Originally Posted by drittal

An under inflated tire will wear uneven, cause excess heat that could lead to failure.

You've got to stay on topic. I was responding to the question if lowering the max pressure causes uneven wear. It does not. The only time low pressure is an issue is when tires are UNDER inflated. That is when there is an issue.
You need to talk to a Nascar team to fully understand how minor pressure changes affect performance and then talk to a tire engineer to understand the SCIENCE of tire pressure.
This is no mystery.

[IC2]

First of all, as you have said, it's a truck - Super Duty is right on the windshield to tell you that.

Now, that's off my chest, my sig F250 not only has the 5er option, it also has the camper option which puts it at the top of the F350 spring system at a 12,100 pounds rating based on actual spring part numbers checked against a Ford parts book. Does it ride rough - well that depends on your definition of rough. I also have air bags to level out and stabilize the 5er but they are only run at 10 psig empty and 20-30 loaded. I run 80/65 pounds pressure in the tires, dropping them each by 10 pounds for winter driving. This year when I needed new tires, decided on the optional size 275/70-18 Michelin instead of the 275/65-18 I had on it previously to pick up a couple hundred pounds more capacity. Not a good choice for riding comfort as they are harsh. I also have KYB shocks rather then the much 'beloved' Bilsteins. The Bilstein's that I put on my last truck turned it into a lumber wagon. Yes, they did the job on that last truck, an '06 F350 but at the expense of riding comfort.

Now with what I've said and what others have mentioned, we still don't know what you really expect for ride comfort as these Super Duty trucks are not necessarily built for boulevard cruises but to work. I also wont mention the Gov't Motors or the Fiat offerings as those folks have their own ideas.

[Fishalaska1]

Originally Posted by 09 harley

Rather than run your tires long enough to see a change in wear pattern, which could take quite a few miles, it makes sense to use what experts say is the correct pressure for the load being carried. Of course you are free to do whatever you want it would just seem that using the correct info makes sense.

It doesnt take miles to determine a wear pattern. It takes 5 feet of dry concrete after driving through water. You can see exactly how your tires will wear.