So I went to the dealership to have my tires rotated on my dually.  They asked how I liked them.  I said just fine, but I was disappointed that they only put 65psi in them all around when I bought them and had them installed earlier this year.   They're 10ply load range E rated at 80psi.  They went by the door sticker.  Now, it seems to me, based on all that I've learned here, that tires should be inflated to their max psi for the utmost safety and longevity of the tire. Or is that only for trailers? Going 15psi under the tire's rating doesn't seem like a good idea to me.  Did I sound like a dummy telling them that the tires should have had more air?  Should I run a tire rated for 80psi at 65 in the duals? Yes, 75-80 makes a rougher ride, but I don't own a truck for luxury.  Should I deflate my tires some?  My trailer is VERY heavy, and I am afraid that if the duals have 65psi the sidewalls may be closer together than I'd like to see. Advice?

Amanda

PS: They told me that my rear differential was leaking.  I checked the fluid on Saturday, and today (tuesday) they said it was leaking and needed welded.  The fluid was still full. Now, I told them that if it was leaking, it must have started suddenly.  I check these things....then all at once several guys are investigating my differential and one says that it's not leaking from where they said it was. There was fluid around the plug, and perhaps it was not tightened down from my checking the fluid level. It looks to me like they smeared it so it looked like it was leaking. I had them clean it good with brake kleen and I said I'd watch it. It looked like the fluid was coming out of the right side of the differential, where the axle goes in. A man with a flashlight said it's not leaking from there.  How'd the fluid get up there then?  It seems awful fishey to me. This is from a reputable dealership.  

As I remember the thread... Max tire pressure was recommended for trailer tires.  Since the trailer tires don't drive or steer, the max pressure adds to the tire life and fuel economy of the tow vehicle.

For the tow vehicle, follow the manufacturer's recomendation for tire pressure.

A Chad says, this issue has been repeated many times with proponents in each camp. One thing that was not mentioned in this thread, was the usage of less than a maximum tire pressure rating whenever dual tires are used. The tires have a lower recommended maximum pressure when used in a dual configuration, than the higher pressure when the same tire is used in a single wheel set up.

At the web sites for various tire manufacturers, you will find that the tire load ratings are stated by the manufacturer at their maximum recommended tire pressure. This is what is stamped on the sidewall, not the door jamb.

A while ago, I was checking the undercarriage of my truck, and found fluid seepage on the rear differential. When I cleaned and wiped down the area to pinpoint the leaking spot, I was surprised to find it originating from the surface of the differential cover plate.

The cover plate had actually rusted from the outside in, sufficient to cause a leak. When I posted my finding in this forum, through other threads, I found this was a common problem that also included engine oil pans. I've been around mechanical items all my adult life and have never seen this happen. Quite a surprise.

Gard