From what I understand, the high load rated tires are supposed to be inflated to near max pressure. At that pressure is where it has it's load rating. I suppose you could use the drive through water/chalk method, and that ?may? tell you how low you can go. But, it may not.
As I mentioned, I found that the truck literally jumps over bumps in the road when I inflate the tires to max (80psi in my case). If I go down to the 55 psi Ford recommends with whatever stock tires came on it, it multiplies the "truck steering". Meaning you have to work a lot harder to keep it going straight. I found with the truck unloaded the pressure it works best at is around 65. When I tow a heavy trailer, I up the rears to 75 or 80 and the fronts to 70. When I pull my open race car trailer that comes in at around 5K, no adjustments necessary. Don't even notice that thing behind me. But if I borrow the big enclosed trailer at 8.5K and significantly more tongue weight, the truck will get squirmy without upping the pressures.
As I mentioned, I found that the truck literally jumps over bumps in the road when I inflate the tires to max (80psi in my case). If I go down to the 55 psi Ford recommends with whatever stock tires came on it, it multiplies the "truck steering". Meaning you have to work a lot harder to keep it going straight. I found with the truck unloaded the pressure it works best at is around 65. When I tow a heavy trailer, I up the rears to 75 or 80 and the fronts to 70. When I pull my open race car trailer that comes in at around 5K, no adjustments necessary. Don't even notice that thing behind me. But if I borrow the big enclosed trailer at 8.5K and significantly more tongue weight, the truck will get squirmy without upping the pressures.
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