I carry a 9'10" Lance camper on my '02 2500 4WD, and often tow a small boat. Total weight of truck and camper is well over 10,000 lbs. I also have the Rickson 19.5" chromed steel wheels with 275 tires, inflated to 80 psi. Recently I took the truck and boat to Puertocitos, Mexico, on the Gulf side of the Baja about 50 miles south of San Felipe. The last 25 miles of that road is a real bear. Narrow, broken pavement with chunks and sections missing, and big potholes. Even down to 5 - 15 mph, (and walking speed thru some) the truck hammered and pounded pretty good. Seems to me that it'd be easier on me and the truck if I could lower the tire pressure to let them absorb some of the jolting, but the question is - how much ?? I don't want to damage the tires by running them TOO soft. I have an onboard air compressor for the air bags, so re-inflation isn't a problem. While down there it was necessary to run on the beach some, so softer tires would be a benefit there, too. What do you guys think a safe minimum pressure would be ?? Thanks all. Lar.

 

I'd run the tires at 50 front 45 rear while offroad. If you have heavy load range tires like E you don't want to go much lower as the sidewalls are stiff and may get damaged with too much flex.

 

Thanks Bill. Mine are load range G, so maybe I'd best stick with 60 psi. Lar.

 

At the slow speeds they'd be hard to hurt. At higher speeds get the weight for each axle and use a air pressure vs. load chart.

Airing up truck tires with the little 12v pumps is darn near futile though...so be prepared if you air down.

 

biglar,

What shocks are you running? I too have the Ricksons and my only complaint, if that is that they are rougher than the stockers. I have Kuhmo's tha I run empty at 75 psi front and 65 psi rear. This gives me the most even wear. These are load range H. I have been looking at getting the Kelderman Air Ride system. I just don't have the $4,500.00 or so for the complete system with the four link rear. Maybe someone on here has it and can comment on how much better if at all it made the ride on rough roads.

Michael

 

Now there's a thought I hadn't thought about. :-) I've got the Rancho 9000's set on 5. If I get under there and spend 30 seconds to set them back to 1, it might just help some. We're planning another run down there in mid-January, so I'll give it a go. I agree that using the little 12 vdc pump takes a while, but I have used it and it does work - albeit slowly. I don't even want to THINK about a hand pump. Incidentally, I thought that since the tires (Coopers) are rated at 110 psi, I'd run 'em at 100 with that heavy camper. Nope. The truck was squirrely on the highway, like it was balanced on a ball or something. A little steering input caused a lot of slewing around.........very unpleasant. 80 seems to work quite well, but still a little unstable. My main concern on that rough road is for the expensive truck, but truth be told, the boat fared far worse. The stiff springs on that little trailer had that poor little 15 ft aluminum boat airborne more than a few times. Lar.

 

I drove that road 3 years ago with my Lance also. It's probably in worse condition now. The next 200 km south along the Sea from Puertocitos is just rock and gravel, and that was a nice trip through wilderness. My truck has the standard 16" wheels and I had stock Michelin LTX on it. Because of the rocks I didn't want to use less than my usual 80 rear and 60 front tire pressure so I set my Rancho 9000 down low for comfort. Very slow going anyway. You could probably use a little less with your big tires, but not much less to protect the sidewalls. Like Rattletrap said use a load Vs pressure chart, but use the recommended pressure at all speeds. People who say different don't know much about tires.

 

biglar,
Sounds like a rough road! We got some of them up here too I only have 16" tires (Michelin LTX M/S) on my Alcoa's, but I keep 'em at 80 year round. Camper on or not, and it's quite comfortable.
Did you buy your Rickson's straight from them or through a dealer?

 

Moose10,

I ordered mine direct from Rickson. They are great people to deal with. This was my second set. The first set I ordered, I got the 19.5" x 6" with 225's, thinking i would not ever want to run a wider tire. Well, after 89,000 miles out ot the 225's (I should have gotten more, but i am very hard on tires), I wanted a bigger tire. They strongly recommended against running a 245 on the 6" rim, so I ponied up more cash for the 6.75" wide wheel. They posted an ad on their website and I quickly sold my old wheels to offset the cost of the new ones.

Michael

 

I never have seen one of these "load/pressure" charts. On this next trip, we'll prob'ly take a look as far as El Huerfanitos or a bit more. Just bought a used 16' fiberglass center console boat and will pick it up Friday. Gotta get back down there for a good break-in. :-) I think the gravel/rock roads are easier on everything and everybody than that awful broken pavement. I worry more about the camper than the truck - it really gets slammed around up there, even taking it very easy. Lar.

 

I got mine straight from Rickson, too, and they were VERY good to deal with. I don't hesitate to recommend them to anyone. I only got about 50,000 miles out of the Bridgestones I got from them, but I drive it hard and the camper lives on it year round. The Bridgestones had a constant high pitched howl to them that 'bout drove me nuts, and wet traction was poor. Glad they're gone. I like the Coopers, but they're smooth, and I don't even want to think about hitting snow or ice with them. BTW, I lied earlier.....I just went out and looked at the truck and those Coopers are 245/70R19.5 - not 275's. Sorry. I wouldn't want any greater diameter, because I'm too high geared as it is. I would like to go wider tho', but there isn't much choice, and kinda like you, I'm limited by the 6.75 rim width. I feel MUCH more secure with those extra heavy duty tires on my very heavy rig. Lar.

 

Off-roaders air down all the time (wayyyy down). The tire pressure ratings are for over-the-road conditions (normal speeds).

Since your truck is significantly above GVW...yes you will have major oversteer if the fronts are too hard. been there...done that. You can safely run the fronts down to about 50 psi with your rig even at highway speeds. You can get a pretty good idea looking at the load rating for "D" tires (50 psi) which would handle teh front, but not the rear when loaded up.

Goodyear's site has a load chart. I don't have a link handy.

Cab-overs add very little weight to the front axle. Based on my significant experience, add about 2000# to whatever the weight sticker on your camper says. Add that to 3000# (empty) for the rear and use 4500# for the front axle. This will get you quite close (on the generous side) short of a scale.

 

You will find a load/inflation chart here: load/inflation chart Keep in mind these charts list the MINIMUM inflation for the corresponding weight. This means you should visit a scale capable of weighing each wheel as well as each axle.

 

I don't think it is worth the extra for the 4 link rear, I almost thought they even removed that from their site as the Keldermans said this themselves. Rather than the 4 link rear they use the stock springs and have a setup that ties one end of the leaf spring to some extra frame (with firestone airbags between) which doubles as a class V hitch. This method works out to about a fifth of the previously mentioned price.

 

Maybe so, but I would still want the front system. So, you are still looking at $1,900.00 for the front and rear. I was wrong on the price for the 4 link and the front. It would be $3,550.00. I would still find it hard to believe that a modified leaf spring set-up would ride as good as a four link.