Oversteer / wander

[Automobilist]

Posted this issue on the Freightliner Chassis forum, but no responses.

Recently replaced tires on our 2002 Winnebago Journey with Toyo's. Also had the shop do an alignment, at least I paid for an alignment... First trip, the coach was really hard to control. Wandered all over the place at the slightest wind or passing vehicle. By wander, I mean it felt like the tail was rotating, causing the front end to wander. We had recently driven the coach from Mississippi to San Diego, and it had driven well on the old tires. (Michelin) After driving a couple hundred miles, I lowered the front tire pressure from the shop set 105 psi to 95 psi. That initially seemed to help. Last weekend, we pulled our 5,000 lb trailer for the first time, about 600 miles. Had to constantly correct steering. Very fatiguing... Lowered front tire pressure again, to 90 psi cold or about 98 psi hot. Helped a tiny bit, not much. The trip home was a real drag, with winds over the Grapevine, and again every passing vehicle making the aft end sway. Not a fun ride. Once at home, found the left inner dual tire really low. All tire temps were good except for the low one, and it was about 30 degrees hotter than the rest. I did buy a TSTT tire monitor system, and have had trouble with it from day one. Currently, it doesn't show a reading on two of the tires, including the soft one. Not much help when we needed it to work...

Thoughts, suggestions on curing the wander? My plan now is to remove the TSTT system entirely, reset all tire pressures, run it on the highway and check tire temps with IR thermometer.

[Mr_D]

Originally Posted by Automobilist

Posted this issue on the Freightliner Chassis forum, but no responses.

Recently replaced tires on our 2002 Winnebago Journey with Toyo's. Also had the shop do an alignment, at least I paid for an alignment... First trip, the coach was really hard to control. Wandered all over the place at the slightest wind or passing vehicle. By wander, I mean it felt like the tail was rotating, causing the front end to wander. We had recently driven the coach from Mississippi to San Diego, and it had driven well on the old tires. (Michelin) After driving a couple hundred miles, I lowered the front tire pressure from the shop set 105 psi to 95 psi. That initially seemed to help. Last weekend, we pulled our 5,000 lb trailer for the first time, about 600 miles. Had to constantly correct steering. Very fatiguing... Lowered front tire pressure again, to 90 psi cold or about 98 psi hot. Helped a tiny bit, not much. The trip home was a real drag, with winds over the Grapevine, and again every passing vehicle making the aft end sway. Not a fun ride. Once at home, found the left inner dual tire really low. All tire temps were good except for the low one, and it was about 30 degrees hotter than the rest. I did buy a TSTT tire monitor system, and have had trouble with it from day one. Currently, it doesn't show a reading on two of the tires, including the soft one. Not much help when we needed it to work...

Thoughts, suggestions on curing the wander? My plan now is to remove the TSTT system entirely, reset all tire pressures, run it on the highway and check tire temps with IR thermometer.

What pressure is required to support the weight of your rig? That's the ONLY way to set the correct pressure, not how it handles.
If you have driven the rig much with 20% less air than the manufacturers charts for your rigs weight you may have already damaged the tires beyond repair.

[Triker56]

Looks like you need to weight all 4 corners to know what air pressure to reset too.
Then put the pressure in the tires that the tire manufacture has for your size tires plus 5 PSI.

Then get all the sensors working on the TSTT

Go for a drive and if it still wanders. A Safe-T-Plus or Steer Safe may be needed.

[JimElliott]

Did it overstear with the old tires?

Jim

[Mike Canter]

Automobilst, my question is when they did the alignment did they change anything? Did they provide a before and after data sheet showing you what is was and what they changed it to. The constant correction of steering can be caused by having too much negative caster in the front end or the toe in being set wrong. I like as much POSITIVE caster as the chassis specifications call for so it will track straight and not follow ridges in the road. I would call the guy who did you alignment and telling him what is happening and have them check the alignment again.

[Automobilist]

Good point, Mike. Thank you. I will do that tomorrow. As mentioned in the original post, it drove fine before the new tires & "alignment". BTW; when I came home from work today, the left inner dual showed zero pressure... I tried filling it, and the valve stem kept leaking. Replaced the valve core and it aired up fine. We'll see...

Ed

[Sammie]

Originally Posted by Automobilist

Posted this issue on the Freightliner Chassis forum, but no responses.

Recently replaced tires on our 2002 Winnebago Journey with Toyo's. Also had the shop do an alignment, at least I paid for an alignment... First trip, the coach was really hard to control. Wandered all over the place at the slightest wind or passing vehicle. By wander, I mean it felt like the tail was rotating, causing the front end to wander. We had recently driven the coach from Mississippi to San Diego, and it had driven well on the old tires. (Michelin) After driving a couple hundred miles, I lowered the front tire pressure from the shop set 105 psi to 95 psi. That initially seemed to help. Last weekend, we pulled our 5,000 lb trailer for the first time, about 600 miles. Had to constantly correct steering. Very fatiguing... Lowered front tire pressure again, to 90 psi cold or about 98 psi hot. Helped a tiny bit, not much. The trip home was a real drag, with winds over the Grapevine, and again every passing vehicle making the aft end sway. Not a fun ride. Once at home, found the left inner dual tire really low. All tire temps were good except for the low one, and it was about 30 degrees hotter than the rest. I did buy a TSTT tire monitor system, and have had trouble with it from day one. Currently, it doesn't show a reading on two of the tires, including the soft one. Not much help when we needed it to work...

Thoughts, suggestions on curing the wander? My plan now is to remove the TSTT system entirely, reset all tire pressures, run it on the highway and check tire temps with IR thermometer.

I also just had Toyo tires installed on my 2006 Journey 36G. I run 85psi in the front tires and 95psi in the rear. These pressures are what is called for on the Toyo tire pressure chart per my coach weight. I have little or no wander when driving on smooth flat roads. The freightliner chassis has a steering bellcrank that can be replaced by a Supersteer model which will help with the need to correct the steering while driving. Also the Motion Control Units are very helpful. See the link below for information.

Brazel's RV > Suspension Products

Sammie

[VanDiemen23]

How big is the coach? I have a 33' beaver, 26Klbs, with only 8K on the front axle, new toyos, and the fronts are 80, backs 85. 105 if around the same weight would make it really light on it's feet...then trailer takes more weight off the front axle.

Compounding that, high winds if the coach is short will make it weathervane about the rear axle. Only solution is to slow down.


Too much caster can be a culprit. My coach was spec'd at 5 deg, was found to be 15 deg. This will induce phase lag in the steering, and you will play a constant game of chasing the center.

High pressure, short coach, high winds, too much caster, high road crown, got me stopped by a cop shortly after I bought the coach - he had a report I was drunk!

[450Donn]

My first thought is tires. I have over the years only had one set of tires that would not work. Dealer replaced two of them with no change. And then put Michelins on and no more problems. I suspect that is your problem

[Dutch Star Don]

Automobilist.....What was the Load Range on the old and new tires?

If they are the same, my guess would be that you're overinflated. I'm not that familiar with the Toyos, but I think many of the sizes don't come designed for RV's. They may be a steer tire, but may be stiff for a good ride on an RV. I'm guessing your Journey is pretty light as RV's go.

You need to get your axle weights and double check them against Toyo's chart. It made be a little scary to run them as low as suggested.

I run the Goodyear G670's and just replaced the four rears after 41000 miles. They had some more than desired bad wear on the outer edges, but made it safely to 41000 before I replaced them due to age.

When I replaced them, I bumped the pressure up 5 psi on the rear and 10 on the front to try and reduce some of the wear. Our first trip out the coach was wandering all over the place. I put the pressures back to what it was and everything is fine.

[Automobilist]

OK, anyone know of a public scale in the north San Diego county area? Better get there and see what the thing really weighs...

[Mr_D]

Originally Posted by Automobilist

OK, anyone know of a public scale in the north San Diego county area? Better get there and see what the thing really weighs...

Try and get four "corner" weights, then go to Toyo's site and find the load/pressure chart for that tire size and model. Use the highest position weight on an axle to set the pressure on all tires on that axle.
Michelin has a good discussion of the process in their RV Tire Guide

[Ed-Sommers]

I recommend Optimizing Tire Pressure

Ed

[fxdave]

my toyos did that for the first 800 miles or so