That's the point of the air suspension, to remove sag. And yes, having the air suspension active while setting a WDH will cause the settings to be incorrect. I'm sure they are still helpful even when not completely dialed in, but I couldn't speak to if they could make anything worse.I don't own my own TT but rent them from rvshare.com. So far they have all come with WDH's but I never knew that you could tune them for a specific setup. Are they helpful even when not dialed-in? I felt pretty comfortable last time I towed, not too much sway, no sag with the air suspension.
This and Turin's post are both great feedback. Yes, taking additional passes without trailer and without the WDH engaged would reveal more info and the tongue weight. Will try that soon. In the meantime the published specs, while not 100% accurate, nevertheless would provide some rough insight. In my case, it looks like the steer axle is normally around 3200# and the drive axle around 2200# (unladen), and that must be without fuel if the drive axle is so low. As you say, at 3500#/3900# I'm below both axle ratings, and I have largely replaced the steer axle weight, if not exceeded it a little. Seat of the pants analysis is that the setup feels much more relaxed and stable than it did before.The Andersen is doing its job if it has replaced your unloaded steer weight. Unloaded steer weight Ideally being taken from a truck only scale slip. But 3,500 should be about right for a limited with Hemi & Etorque. You also need the unloaded truck only weight slip to use with the slip you posted to calculate your actual scaled or seen with WDH (dynamic) tongue weight.
Assuming tongue weight is in the 10 to 15 percent of gross trailer weight you should have a very safe stable setup. IE it looks to have replaced unloaded steer weight and is below steer axle rating. Drive axle is also below max axle rating. 13,720 is also below CVWR combined vehicle weight rating. All which suggests a safe stable tow setup. It also shows the truck axles shouldering more weight than the trailer axles. This is not necessary but is ideal as the tail is less likely to try and walk the dog as the saying goes.
With both slips you can calculate actual seen tongue weight, gross trailer weight, the effectiveness of your WDH setting and therefore can adjust your WDH and bed and trailer loading to get or work toward the most stable setup. From experience with many box campers I work toward 12.0 tongue weight. It’s enough for sway & wind stability for towing 65 mph with a half ton truck but doesn’t put more weight & strain on your truck than necessary. With a flat bed 10 percent is enough.
I had the same issue(my tank is at the back of the trailer too), filled up some water to be able to use the bathroom on the road...wound up putting too much water in and had the exact same feeling you explained. Used some water at the campsite and the last leg of the trip was much better.I’m pulling a new Transcend Xplor 265BH with a 2019 Limited. 33ft long, 6734 dry with 654 tongue weight (as built per VIN sheet from factory). It’s probably around 8k loaded. Started with an Andersen and hated it, so swapped it out for a 10k Equal-i-zer hitch. RV dealer setup the hitch with trailer relatively loaded but no water, and truck empty. Driving it that way with only me in the truck, it pulls like a dream.
Took it about 45-60 miles this weekend fully loaded, and it was a completely different story. Outbound I had a full water tank (62 gal/516lb) and a loaded truck with me, wife, son, 2 dogs, and 65 quart RTIC with drinks and ice. I was getting pushed around like crazy, white knuckling it at 55 mph, & probably had a good 20 mph cross wind. I saw a CAT scale, so I did a single weigh just for reference, as I couldn’t really change anything at that point and only had another 10 mins to go. I was overweight on the truck, but I don’t have any unhooked weights to compare to.
Coming home, I had dumped all the tanks. Interesting thing about this trailer, the fresh water tank is at the very back, so that’s 516lbs of back end weight gone. I stopped at the same scale and weighed again. The return trip home felt completely solid and comfortable, and if it weren’t for the scale showing me being overweight, I never would have known and wouldn't be looking to change anything.
I'm thinking the water in the trailer made me tail heavy and the load was therefore unbalanced. I’m going to do another round of scale weighing before the next trip. Hopefully I can move some weight (the cooler) from the truck bed to the trailer over the axles, and also adjust the WDH to get the measurements closer to the GVWR, and shift more from the drive axle to the steer axle. Max load capacity is 1154lbs, GVWR is 7100, but GAWR is 3900 front and 4100 rear for a total of 8000 GAWR. It does strike me as a little odd that there is a 900 lb difference there. If it drives comfortably and solid, do I really need to be all that concerned about being 260 over the GVWR even though it’s under the axle limits? Any advice?
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What size is your truck? 1500 and what trim? Didn’t think the 1500 could handle a fifth wheel? I currently have a 1500 bighorn with the 5.7 Hemi and 3.92 rear. Pulling a 35 foot travel trailer and overall happy but had to add airbags for the tongue weight (800lbs).I'm pulling a 36" Sandpiper fifth wheel at 9000# approx. with 1000# tongue. Towed from Tucson to central Washington with no problems.
here is my biggest tow. 8429lbs in this pic scaled ready to camp.View attachment 43383