freightliner suspension

"gshantz"....I had the same problem years ago on a Class C Jamboree that I owned. It originally came with Michellin tires. It ALWAYS handled well, but eventually needed tires. I went to America's Tire Company for the purchase. I was in my late 30's with a family and needed something less expensive than Michellins. America's Tire Co. made me a good deal on Kelly Springfield tires, which are a sub brand of Good Year.

A few weeks after installing the tires we left on our yearly boating trip about 400 miles away and a trip we had made a dozen times in the motor home. Five or six times during the trip we traversed some large sweeping curves and "S" curves on HWY 99 in California. On all of the curves, at highway speeds, the motor home felt like it was "rolling" right off of the tires. It did EXACTLY what you described. As you made the turn, the chassis was following the turn, but it felt like the coach would take a second or two to come around in the direction of the turn. This was a very uneasy feeling.

I knew exactly what the issue was.....the sidewalls were not stiff enough to keep the motor home from having the rolling effect. The Kelly Springfield tires were the same weight and load rating.....they just didn't work on my setup. When we returned from the trip, I paid the additional money to put new Michellins on, like I had before. Problem solved.

You need to change to something else. Demand the that the tire store, for safety reasons, move you into another tire. Since you didn't have the issue with the Michellins, I would bite the bullet and pay the difference.

carringb wrote:
M154's are pretty aggressive for a motorhome. They have more tread squirm than highway-tread tires, and when you install the on the rear only, you often get a little over-stear sensation, but its only from the tread squirm. It will get better as the tires wear.

You can also fix this by installing the same tires up front, because then they will also require more "slip-angle" to change direction, so they balance out.

PS - I run M55's, which are the same tread pattern but in light-truck flavor. I also ran M154s on several medium duty trucks.

Never had any tread squirm from M-154 Toyo tires. They are a very good tire.

M154's are pretty aggressive for a motorhome. They have more tread squirm than highway-tread tires, and when you install the on the rear only, you often get a little over-stear sensation, but its only from the tread squirm. It will get better as the tires wear.

You can also fix this by installing the same tires up front, because then they will also require more "slip-angle" to change direction, so they balance out.

PS - I run M55's, which are the same tread pattern but in light-truck flavor. I also ran M154s on several medium duty trucks.

Well, I'm a little slow getting back here after my trip to Tucson. I had changed the tire pressures according to specs as mentioned above (90r and 80f), and had resolved to not obsess with handling and just enjoy the ride to Tucson. (About 4 hours away) I would say that the difference in ride was very subtle and for the better, but in general had to struggle to maintain my own lane. There was some cross wind, but nothing unusual. I found the drive to be much more tiring than it used to be. Very disappointing.

When time and money permits, I'll have the alignment thoroughly checked out. Need a seal coat on the roof first before winter. Supposed to have a big winter this year. Fortunately, in Arizona, our roads never stay icy for long and we will likely head south around Christmas. (Weather permitting.)

Again, thanks for all the posts and suggestions.
GS

gshantz wrote:
Except for dropping the fronts down 20 lbs to 80 PSI as you point out, I'm nearly at Toyo's specs. (Thanks for the page link.) I'll do that before our next trip over the coming holiday - only 50 miles. :-) Right now I need to save some more pennies before taking it in for a checkup. I like your suggestion of things to have them check up on. It just blows me away as to how changing tires could make all that much difference in the ride.
As I said, I'll be sure to let you know when I get further info.
GS

I dropped my steer tires 10 pounds and my tag axles 20 pounds to get them to the proper manufacture recommended specs and it made a huge difference. Very noticeable and favorable.

I look forward to hearing how your first trip goes with the new pressures.

Gerald, in your first post you said "The tread on the tires I replaced were not worn, just old and cracked." I took that to mean the front tires were evenly worn... one edge was not worn more than the other side although there were not all Michelin. Assuming evenly worn and good handling before, it's not an alignment problem.
With two people and a tape measure you can check the toe in by measuring to the same spots on the inside of the tire (usually a rib several inches below the tread). You want the front measurement to be around 3/16" less than the rear on a 22.5 tire. Doubt you will find it out of spec.
Let us know how it handles with 80F/90R psi after your next trip.

holstein13 wrote:
I think I found the Toyo RV inflation guide here.

It would be nice to know your corner weights, but if your tires are equally loaded, it looks like you would use 90 PSI in the front and 90 in the rear tires as well. So I think you are correct.

I would definitely call Freightliner and get a good four corner alignment done. Look up your ride heights and have them adjust that as well. The rear wheel alignment can be as important as the front -- especially the way you are describing the rear going wide. While they are checking your suspension, have them check for loose connections, ball joints, etc.

Except for dropping the fronts down 20 lbs to 80 PSI as you point out, I'm nearly at Toyo's specs. (Thanks for the page link.) I'll do that before our next trip over the coming holiday - only 50 miles. :-) Right now I need to save some more pennies before taking it in for a checkup. I like your suggestion of things to have them check up on. It just blows me away as to how changing tires could make all that much difference in the ride.
As I said, I'll be sure to let you know when I get further info.
GS

And you are correct that he did post "245/75R 22.5 Toyo M154".

Ivylog wrote:
Would help to know if they are 245/75 or 255/70. Assuming 245/75/22.5 then holstein13 is correct for the rear...90, BUT the fronts only need 80 (3860 single) for his 3670 lbs.

You are correct. I think I read the wrong line on the chart. Steer should be 80 and duals 90. I believe the OP said the tires are 245/75. But he didn't explicitly say all the tires are the same. Good catch.

Would help to know if they are 245/75 or 255/70. Assuming 245/75/22.5 then holstein13 is correct for the rear...90, BUT the fronts only need 80 (3860 single) for his 3670 lbs.