Tow vehicle performance after change in TV cargo

[Gshellhammer]

Just returned from a trip to Arkansas. While there decided to replace TV tires. I was very happy with my setup and performance that I just tried to replace with identical tires. Tires were replaced just prior to returning home.

Data: TV - 2010 Grand Cherokee hemi with towing package. Trailer 2001 25ft Safari AS sleeper6. Original tires Goodyear Fortera HL 245/60r18. New tires are Goodyear Wrangler SR-A 245/60R18 Load/Speed rating 105T. OEM tire pressures suggested 33lbs. Put 38lbs. in new tires. Max tire pressure on tire sidewalks is 51lbs. Reese hitch with trunnion style WD bars. No sway control. Ball is set 3/4" above coupler before load. After load front measurement at front TV axle does not drop. After load rear TV axle drops 1.5".

So immediately after leaving with new tires I noticed a dramatic difference in sway. Not only did large semis suck me in but small pickups also caused a pull. This was a dramatic change. Completely rechecked my hitch settings since I had new tires. All measurements were the same. Decided to increase tire pressure to 44lbs as my original tires were maxed out at 44lbs. After driving about 50 miles on freeways, I felt that the sway was somewhat better but internet advice from various websites reiterated following OEM suggested pressures. I stopped at a rest area and dropped the pressure back to 38lbs. So I fought the swaying all the way through Atlanta.
As we got north of Atlanta, I realized that there was another change in my TV. I did not bring my Toolbox. I needed the room for a number of boxes of china. And those boxes were now gone. They went at the same time we put on the new tires. So at the stop for lunch I grabbed our trays of canned goods stored under the dinette and moved them into the TV.
The result was just as dramatic. Gone were the scary semi truck pulls. Gone were the pickup truck pulls. Now I could start to enjoy the drive.
We have been traveling the Eastern U.S. For the past year and a half. I just realized that I always have brought a toolbox.

So my question is this. Why would 50-75lbs in the back of my Grand Cherokee make that much difference? And what can I do about it for the future? If I shorten the WD hitch with one less link and nose down the front of the TV help?

Your advice will be greatly appreciated.

[ROBERT CROSS]

"Reese hitch with trunnion style WD bars. No sway control."

75lb shouldn't make that much of a difference.....no sway control would?

The reviews on those tires are 3 out of 5....why were they chosen?

Bob

[Tuco]

I had a similar experience with new TV tires. Solid as a rock before and squirrely after. It had nothing to do with load in our case. It took time for the new tires to square themselves off. It was like the truck was on the "balls of its feet". After about 300 miles the truck was back to normal, but wow that 300 miles was rough!

[Gshellhammer]

Why were they chosen? They were suggested by the tire dealer. I was away from home. Not an excuse just a reason. The change that occurred was dramatic. I felt the change within five miles from the rest area's on ramp. It only took a couple of truck passes to to tell my wife that things were better.

[AWCHIEF]

On my 2011 JGC Hemi I went from the OEM stock tires to Bridgestone Dueller H/L, P265/50R20. Really dramatic improvement in handling and feel. I run them at 39lbs. These tires are highly recommended on the Jeep Forums for towing and all around use.

[ROBERT CROSS]

Concentrate on the tires when there is no sway control?.....

Just what I would do, set PSI to the max sidewall value or just a bit less, add sway control and visit the scales to get the proper WD set-up.

But that's just me.....

Bob

[nrgtrakr]

Take the TV tires up to 50 psi and see what you think.
Our F250 is squirrely when the tires are low.

[Gshellhammer]

I plan to increase the tire pressure to 50 psi and test drive our local freeway. I will report back here with the results.

[Widget]

Is your dinette in the front or rear of your trailer. I recently had about 100# extra in the rear of our trailer an it felt similar to how you described. Weight out on the next trip and all was cool. In my case I believe we are on the edge of low tongue wt. I haven't checked with a scale.

I'll second the tire wear in as well. Last time I got new treads they were particularly squirmy for the first week or so. Then settled right in.

Add the canned goods back to the trailer and see if you can repeat.

[Paul and Tam]

One thought - You may have selected the wrong load range for your usage of the vehicle. I noticed that the tires you bought are 105T load rating, or SL. Take a look at your sidewall to see the maximum load capacity for this tire. My guess is that you are running near that load on the rear axle when you have the trailer attached. 50PSI will help, and I recommend running the fronts at 50 as well for weight transfer during braking.

The last tire change on our tow vehicle (horse trailer, not camper) I went with XL rated tires for the higher load rating. My wife's initial complaint was that the TV drove more like a truck. That was true - the stiffer sidewalls did not absorb little bumps as well as the p-metric tires that were previously on her SUV, but the load rating per tire went from 1600 to 2200 lb. I like having 1200 lb of safety on the rear axle when the TV is used as a truck.

Good luck, and I hope running at 50psi helps.

[Gshellhammer]

Thanks, I will look at my options. If the increase in psi fixes the problem and I am not exceeding load capacity of the tires, I will let you know the results. If I made a $1000 mistake, I will fix it.
I thought I did things right.

[Gshellhammer]

Widget, the dinette is in the middle. My heavy weight is almost directly over the axles. I will be trying the movement of the weight.

[JCWDCW]

"50PSI will help, and I recommend running the fronts at 50 as well for weight transfer during braking. "


I'm not sure you want to run front tires at max. You need max pressure on rear for load and running cool but front tires at max unless you really transfer a ton of weight forward will give you poor steering control. High pressure without weight will round out the tire and wears center faster....so less foot print under the front suspension. Certainly there is some dive under hard braking, but the equalizers tend to keep the truck even front to back even under heavy braking.

JCW

[Bowmans]

I wouldn't run without a sway control myself. The risk is always there for a good side wind, whether from a large semi or winds.

We run an F150 with a 31' 1979. I can tell the difference when I move 40# from the trailer center to the bed of the truck. I have gotten the load down now to where I can tell whether we are light in the truck bed or front of the trailer and will stop at the first rest area and shift a little. Have you put the box back in the TV and tried out that additional weight with the new tires?

[slowmover]

Tires need a few thousand miles to settle in. This explains the most.

Rig still needs to have WD set on a scale. Fender measurements are a good rough-in, but that's all. Tire slop makes less than ideal WD more obvious.

TV tire pressure needs to be according to load and within door placard range. TT tires at sidewall max.

Best to get individual wheel loads on TV with WD applied in order to set best cross axle tire pressure.

Get these mechanical details attended to before deciding about tires choice.

I never liked the SR-A but it may have changed since 2001. Reading forums and Tire Rack reviews for those with more than 20k on tires is a good idea (as in above post).

Better shock absorbers always a good idea unless what's on there is some high zoot factory type. BILSTEIN, unless KONI available.

[Gshellhammer]

First let me say thank you for all your inputs. If I have learned anything from this experience, it is that there is a wealth of information on the Internet about setting up a WD hitch for a TV. But not everything is standardized. Often the information is debatable and varies with the experience of the contributor.
So I have taken in everything I can and then tested as I could.
I can and maybe will take my rig to a weight scales to get each axle or even each wheel weighed. But I am going to have to find a professional who knows how to interpret those numbers.
I can turn a wrench. And I can apply complex formulas to get answers. But using those numbers correctly is frustrating. I have calculated axle weights, gross TV weights, gross TT weights, etc.
Mathematically, I did not exceed the load factor of my tires. I have over 300 lbs on each tire to play with. I doubt I can stuff my motorcycle in the trunk. So, I will not be purchasing another set. But I would never recommend them.
So I took the trailer for a ride. I pumped up the new TV tires to 50# a pound less than max. I drove it on a windy day without excess weight in the back. The movement of the trailer was expected. Then I stopped and shortened the number of links by one. It did not help and I felt less in control. So we stopped again and lengthened the chain links and moved weight to the back of the TV. I know this is not explainable but the vehicle felt heavier. As if I was more in control.
So results of my non-scientific and non-quantitative experiment. I will leave my tires pumped to max and always travel with my tool boxes (120lbs). If I run into a professional TV rigger, I'll get a price quote.

[nrgtrakr]

Very good! Thanks for the update!

[idroba]

This is probably of no use but my 2012 Jeep Grand Cherokee Overland with full air suspension came with Michelin 265/50 R20's. When they got worn down they wanted to hydroplane when it rained, so at about 30,000 I replaced them with the identical tire. I noted no change at all in towing (I do a lot), still very stable and solid, with absolutely no indications of any sway. The trailer is either a '74 Argosy 20' or a '14 FC 20. The hitch is an Andersen.

I have noted no towing difference if the water or holding tanks are full or empty, they are all behind the axle in the FC 20. In the Argosy the 35 gal water tank is up front. In other words, I have noted no change due to weight shift and distribution.

I have read of tires making a lot of tow stability difference, and you seem to have proved that possibility out. However I have no ideas or opinions as to why it should have happened to you with your combination. Is there any chance your tire dealer will exchange them for some other brand, given your experiences? I doubt that you will find a good solution by either tire pressure changes or moving things around. I would not want to drive a combination which was that sensitive at any rate. It would seem to be on the edge all the time.

I will be interested in how this plays out for you.

[Paul and Tam]

Thanks for the updates. I'm glad the extra pressure helped, and sorry it did not fix the problem.
One question, and no offense intended, but are the trailer tires all inflated to the same pressure?
We've experienced some decreased stability with a low tire on the horse trailer. Trust me, you so not want to have a blow out at highway speeds.