I've done all the suspension mods to my Ex that are recommended for this vehicle. The truck tows very well considering that it's a bumper pull rig towing a decent amount of weight. Now I'm trying to "dial it in", so to speak. If there's a weak link, I believe it's in my wheel/tire combo.

Currently, I'm running BFG AT T/A KOs 285 75/16 (E load range) on the stock wheels. Stock wheels are 7" wide and an 8" wheel is recommended for my BFGs. Even airing the rears to 80psi, I'm getting too much side wall flex which I believe isn't helping the truck's stability.

I'm looking at two options...there could be more.

The first is to simply purchase 8" wheels. That wheel, or maybe even a wider wheel, should eliminate the sidewall flex. The second option is to go with a Rickson wheel/tire combo. I'd go with the 245 70/19.5 in order to maintain the same tire diameter/height. I think the advantage to the Rickson option is that I know I'll be getting a tire that will have very little sidewall flex. The downside is that I'm giving up tread width. The Rickson tire will be 9.6" wide and the BFG 285 is 11.3" wide. My understanding is that the Ex likes to have more rubber on the road to be stable.

Any ideas?

 

Just a couple of questions to clarify things for me.

What effects on your driving and towing do you attribute to the sidewall flex?

What mods have you done to your suspension?

I find it nearly unbelievable that your tires in E load range at 80 psi would have noticable sidewall flex at the weights that the Excursion is able to handle, even with the stock rims. BFG AT's are known for little sidewall roll. It must be something else.

 

Don't waste your money on wheels, that 1 inch of rim isn't not going to make a noticeable difference in my opinion! Hate to see you spend unecessary money! The sidewall height does not change it stays the same no matter what wheel width you use! If you are 100% positive that the sidewalls are flexing than you don't need wider wheels you need to go back to shorter tires like the original 265-75-16E. Wheels are not going to change the tire sizes at all! Anytime you go to a taller tire with a taller sidewall it will give a little more sidewall flex than a shorter tire. Now a 285 tires with a 20" inch wheel would have way less sidewall and would handle pretty well! But upsizing your tires and using the same diameter wheels leaves you with a taller sidewall which can flex more than a shorter one. Width of wheels is not the issue here though for sure!

Odds are your feeling something else that is causing the instability. Do you have Air bags or RAS or stiffer springs installed? That right there helps big time! Stiffer shocks will also help, along with a dual steering stabilizer. Tightening the steering box can also make a large improvement on handling! These Excursions can be a little tricky to get dialed in, but once it is dialed in they do tow great!

 

Actually, the sidewall height does increase from a 265/75 tire going to a 285/75 tire. But it is only 1/2 inch. Not enough to make the difference.

 

Ditto

Something else to think about is tongue weight, which should be 10-15% of your gross trailer weight (with the spring bar tension set if using weight distributing hitch). If it is too light, you could be feeling the effects of an improperly loaded trailer pushing your rear end around. That could easily be mistaken for a faulty suspension or tire setup.

Additionally, using a weight distributing hitch doesn't guarantee proper loading. It is possible to put too much tension on your spring bars causing the tongue weight exerted on your hitch to become less than it should be as it transfers weight to the front axle of your tow vehicle and to the trailer axles.

Before you begin chasing other rabbit trails at great expense, I would load your trailer as if you were going on a trip then go to your local scales to see if the load is properly distributed. When you are done, you have only spent a few bucks; and regardless whether it is the source of your problem, you are assured of how your load is distributed across the axles and the tongue.

I pull a 35 ft., 10,000 lb. TT with no suspension mods and stock sized, E load range Dueler AT Revos. When it is properly loaded the trailer pulls OK, but since I am a safety nut it still pushes me around more than my comfort zone will allow. I don't think the suspension is too soft or the tires are to blame. I believe it is because I have a really long trailer with an inadequate hitch setup (cheapo weight distributing hitch with a single sway control bar). That is why I am upgrading to a much better hitch setup this spring.

Just my$.02...

Stew

 

Suspension and other mods in my sig. It's hard to describe what little off track movement I see, but it is a minor wiggle at times. I've weighed my rig and used the slips to insure proper weight distribution.

The Tire and Rim Assn (TRA), the Rubber Manufacturer's Assn (RMA), and all their members, including BFGoodrich and all other tire makers that sell tires in the <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-comffice:smarttags" /><st1:country-region w:st="on"><st1lace w:st="on">USA</st1lace></st1:country-region>, require a minimum of 7.5" rim for an LT285/75R16 tire. Are they incorrect?

 

I disagree with some other posters here. rims do make a difference as at full inflation the tire can curve up at the edges and focus more weight on the center of the tire and cause wandering. I am running 285's on 8 inch rims, they sit flat on the road at full inflation. see if you can slide a sheet of paper or card stock under the tire tread... if u can, let air out till you cannot get the paper under the tread and see what pressure you are at. Also look at the spec sheet BFGoodrich Tires | All-Terrain T/A® KO | Tire Sizes & Specs for your tire and see what size rim they use for the measurements. generally they are going to choose what they feel is the best rim size for that setup to make their spec measurements... in your case it is 8" with the range being 7.5 to 9... so any way you cut it your rims are still too narrow...
the 19.5 option is nice but a lot of $$$... you will be at a firmer ride due to the nature of those tires. also note that on commercial truck tires the edge of the tread sits directly inline with the edge of the rim...

 

Yes, the 19.5" wheels are some coin. The bottom line is that my truck is due for some new rubber anyway. And finding a good quality, 16" X 8" hub centric wheel is no easy task. A set of four Rickson wheels will set me back $1,100. I haven't got pricing on a set of 16 X 8 wheels. I'm assuming they're not cheap either; certainly not the cost of Rickson wheels. But at that point, you're only looking at the cost differential since I know my current BFGs shouldn't be riding on the OEM wheel.

Any examples of an Ex towing on 19.5" wheels?

 

Stewey,

You seem to have done all the right things and yet you still have some 'wiggle'...

A couple/few of questions though.

1) When you say you weighed your rig...was it loaded as it would be for camping including all people and gear inside the Ex?
2) Do you carry your fresh water tank full or empty and is it consistent going and coming from a trip? (meaning is it full both ways or empty both ways?)
3) Do you ever haul with gray or black tanks full?
4) What type of WD hitch are you using?
5) What is your tongue weight and what size WD bars are you using?
6) Is your trailer level or slightly nose down when hitched?
7) What tire pressure are you running in your trailer tires?
8) What pressure are you running in your air bags?
9) How did you set up your WD in relation to your air bags inflation? (this can prove to be an issue as it 'may' contribute to unloading of your WD if you fill the bags AFTER you adjusted your WD...just thinking as I type here)
10) Do you happen to have your weights handy and if so can you post them? I would like to see the following three weights: (Ex alone, Ex hitched with WD not engaged, Ex hitched with WD engaged)

I have personally experienced the effects of TOO MUCH tire pressure causing an instability...especially when semi's pass or windy days...I backed off my Ex's tire pressure and whalla...stability!

A few more questions...

Have you had your front end checked out recently?...ball joints can be a major contributor to an ill handling Ex and they are prone to wearing out on our trucks...that play in the front end is magnified when towing...just a thought to ensure you aren't chasing the wrong thing...

If you can shoot me some answers to my questions...we may be able to get to the bottom of things.

You've got some of our best helping you out thus far...I just have a couple of questions that weren't necessarily asked and I'd need to see the answers the help narrow down your potential issue. In the end...it may well be your wheels...but let's take a look at some of the other areas first just to be sure...

One way or the other we'll get you dialed in.

Thanks,
Joe.

 

I 2nd what Hemi says!

He really helped me get mine dialed in so I can tow my 30' 11K toy hauler with

confidence now!

 

Just throwing out some base information about the rig in qquestion.

Some specs on the Arctic Fox 29v that he tows from their website:

GVWR: 11700lb
Dry hitch weight 980
Gross dry weight:7860
dry axle weight 6860
44 gal black
67 gal fresh
30 feet including hitch.

He drives a 6.0 PSD 4X4, so his max GVWR for that is 9200lbs. Max GCVWR is 20,000lb. Max trailer load is 11,000lb.
Max GAWR front: 4700
Max GAWR rear: 5250
Base curb weight (From Ford) Front: 4012lbs Rear: 3758lbs Total: 7770lbs

Your sig shows a GCW of truck and trailer of 20,420lbs.


As you can see, the rig is right at the limits for GCVWR. I would be interested in knowing the tongue weight, and all of Joes questions, also.

Joe has asked all the right questions and is the man to see. Armed with them, you can get the advise you need from us. The idea is to eliminate any obvious problems first.

One more question: have you adjusted your steering box?

We also need to keep in mind, after eliminating everything else, that axle wrap could play a part in this due to the weights involved. I don't think so, but just mentioning it.

Bion

 

One other thing that I found from dumb stupidity on my part years ago when I started towing: Never over spring the WD Hitch. It leads to some serious wander problems as the rear axle gets unloaded and the front loads too much. I kept thinking it was something else for a long time, until I finally wighed my rig. Slapped myself in the forehead several times.

So that leads to another question: Who did the installation of the WD hitch on your rig? Was it done for this trailer or a different one and you transferred ?