Squished tires when towing
 

I'm towing a 8200# travel trailer with my 2011 Eco Supercrew max tow and a weight distribution hitch. When I hitch up the back tires look very flattened. Is this because my truck came with P rated tires rather than LT? I've been adding air up to 45 psi. Is that safe?

I'd say tires are at fault, unless the trailer is improperly loaded/weight distribution hitch isn't doing its job and their is too much tongue weight.

I put 3000lbs payload in my f150 with Firestone Destination A/T tires and the bulging was relatively minimal at 35 psi.

The sidewall on my P-rated tires says 44 PSI max cold. So when towing, that's what I pump them up to. I have 650 pounds wet and loaded hitch weight, and my Reese Strait-Line dual cam hitch works pretty good to distribute about 50% of the hitch weight to the other axles.

Weigh the rig three times, once with the spring bars tightened, once with them not tightened and once without the trailer.

Subtract the weight of the truck without the trailer from the total of the front and read axles of the truck when the spring bars are not tightened. That gives you total hitch weight (tongue weight or TW).

Compare the rear axle weight with the spring bars loose with the rear axle weight with the spring bars tightened. The difference is the amount of weight that the WD hitch is distributing off the rear axle of the truck, which should be about 50 percent of tongue weight.

If the weight distributed off the rear axle is not between about 45% and 55% of total tongue weight, then you need to change the amount the spring bars get tightened. Tighten them more to transfer more weight off the rear axle, or loosen them more to transfer less weight off the rear axle.

Since you have those three CAT scale tickets, check the weight on the rear axle when the spring bars are tightened. Compare that weight to the rear GAWR of your tow vehicle. You shouldn't even be close to the GAWR.

Also add the front and rear axle weight with the spring bars tightened to get your gross vehicle weight (GVW). Compare that total to the GVWR of your truck. If your GVW is more than your GVWR, then you're overloaded.

I put 44 in mine and have 1650 lbs on the 5th wheel hitch. My P-metric tires look fine.