I'm a bit confused at to what pressures to run in my tires on my 550.

Their Conti HSR/HDR 19.5 on a dually setup. Pull a 3 horse GN with living quarters. Believe the sticker on it says 12k lbs.

OEM tires were General LMT400's

3640lb Single 95psi max
3415lb Dual 95psi max

Current Conti's are

3970lb Single 110psi max
3750lb Dual 110psi max

Sticker from Ford says to put it at

F - 75psi
R - 95psi

Sticker from Utility Bodywerks (who put the bed on) says

F - 75psi
R - 75psi

So, whom do I believe? Why would Utility Bodywerks spec 20psi less in the rears? It's a cab/chassis with a pickup bed on it. Since the Conti's on it can carry more, should I bump up the Ford spec by 10psi or so?

 

What pressure have you been running? Are you having any problems? are tires wearing evenly? Steer on front and traction on rear or traction all around?


My thoughts are:


The pressure from the tire is the maximum to run for max loading.
The pressure from Ford is what they say for the original tires and the GVWR and or axle rating. They have no clue how the truck will be used.
The pressure from Utility Bodywerks is what they say for the original tires and the GVWR and or axle rating. They have some idea of how the truck will be used and are making a recommendation based on that. Based on the pickup bed I would think the rear axle and tires will see less of a load than the max Ford says is ok so Utility Bodywerks gave a lower number to improve ride and possibly tire wear.


My opinion of what to do. Get your truck to a scale and get the axle weights as you are using it. if you are close to the rating of the tire you need the max pressure per the tire. I highly doubt that you are. Use chalk to see if the tire is contacting the road all across the tread.


Now what I do on my F450. My tires are rated at 95. I am running 95 front 80 rear. I was at 80 all around. I just replaced the fronts with Bridgestone r250 steer tires. My old front tires that came on the truck were wearing more at the edges than the center so I am upping the pressure to try and improve the wear. The rears at 80 are wearing well. I could probably lower some when not towing but am happy with what I have.


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just swapped over to these conti's about 1000 miles ago, so it's too early to tell how their wearing.

I have steer's on the front and drive's on the rear. However, the truck alignment shop I took it to put one of the drive tires (HDR) on the front. He said the steer tire on that side was worn unevenly and pulling truck to the right. (They were used 19.5's). That tire blew out on me yesterday when I was returning home, no trailer or load.

So i'm not sure if it was because it was a drive on the steer axle, sidewall previously damaged and I didn't know it, improper inflation, or maybe just unlucky?

I have them all at 75psi cold currently.

 

OEM tires were load range F, new tires are load range G. Hence the higher pressures and weight capacity.

this seems to be another one of those ... ask 10 people, get 12 answers kind of things.

Coworker, who ran dealership service dept's and tire/brake stores said they would do 10psi less than max on passenger cars, and 20psi less than max on trucks. Which would put me at 90psi F and R. Close to what Ford originally spec'd for the truck.

I'm just worried that running 75psi on a tire that has a max rating of 110psi will cause it to heat up too much and prematurely fail.

 

I agree 100 percent on that. I read thru a bunch of threads about tire pressure, load, and wear when I Got my F250. Now with the F450 everything changed.
I remember seeing a chart from a tire manufacture showing different pressures required depending on the load. You might be able to get something like that for your tires in your size. Probably a long shot. A minimum recommended pressure may be more likely.


Edit here is a pdf from Continental
http://blobs.continental-tires.com/w...ables-data.pdf




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Thank you for that. I did contact them and they sent me info on truck tires, an air pressure table, etc. But it doesnt list a 225/70/19.5 on it ... just my luck. They do have the 245/70/19.5, but not mine.