F-450 Towing and Tire Pressure Question
 

Just finished a 500 mile tow with my F450 (2008 bought new in June 2008), with my new Gooseneck Pace 48 Ft enclosed trailer. I was hauling 2 heavy door cars, and gear to the track which was about 18000lbs.

First of all, the trailer seriously felt better than towing my 24 foot tag, and was super stable, and effortless. I really like towing with a gooseneck, as this was my first time. :)

The question I have is in regards to tire pressures. I set my truck to 80psi all around, and the trailer recommended 110psi. Does this seem like a lot of pressure? My previous tailor recommended about 80psi.

I do the same, up to 80 when I tow heavy on the E rated tires. I think 110psi is a G rated trailer tire? Anyway, I keep my G rated trailer tires at 90, plenty hard in my opinion. My trailer has triple axles so they all carry very reasonable weight. If you have two axles may want to keep an eye on how the load sits on your tires.

It is a triple 7200lb axle trailer. The tires get fairly hot. Would more pressure or less pressure have any benifit? Or should I strictly go with the manufacturers recommendations.

I always go max pressure on all my tires, according to what the side wall indicates. Harder ride on the truck but better performance.

The only way to get the correct answer is to go to a scale and take individual axle weights with the trailer loaded and attached. Since you have a 450 (as I do), it probably came with Continental 225/70R19.5 tires. The Continental Tire website however, still does not list the pressure for the G rated tires. I emailed them about this in March of 2008, they sent me the correct numbers, but still haven't updated their website.

Based on the numbers they sent me, here is the table:

PSI.....Front.......Rear
75...........0.....11,400
85......6,630...........0
90......6,900....12,980
95......7,280....13,660
100.....7,430....13,960
105.....7,690....14,460
110.....7,940....15,000

Yes, I know there are a couple of holes in the table, I'm not sure why I don't have those pressures. The large numbers in my chart represent the maximum axle weights, not individual tires.

You really don't want to either over- or under-inflate your tires; doing either will greatly shorten tire life and perhaps lead to blow outs.

Good luck and enjoy your 450!

Thanks whiteex, good to see confirmation on the concept that there is some variation in what you can run for pressures. I usually move them around based on weight going with the PSI printed on the door of the truck as the minimum (which I never run anyway).

Two things to add: 1. Running 110 psi during the summer with a load SHOULD be taken into account by the tire manufacturer so I would think that it is safe but I would prob run 95-100. 2. I don't think it's worth it, but, you can go and get nitrogen to inflate your tires. It is supposed to be free of any humidity and also claims to not increase/decrease it's density with temperature variation. Therefore, when they get really hot or cold you will always be very close to the number you inflated them to.