MOD Flat spots and tires

[Keywest42]

My class B RV was purchased February 22 with 12,500 miles on the odometer. My test drive did not include highway. On the way home from Ohio to Eastern Pennsylvania, my steering wheel was shaking at 65 through 75 + mph.
I have been through evaluation by Mercedes for alignment, balancing and brakes, wheel bearings causing the problem. There are dully tires on the van. The tires were rotated and balanced. The problem was not at all corrected. The technician and service writer suggested the vehicle developed "flat spots" on the tires for setting in one place for an extended period. They talked about replacing the tires. That is an expensive experiment to resolve the shimmy. I'm open to thoughts and experiences with this problem.

 

[AbdRahim]

It is still under warranty. Check with dealer, or better yet, manufacturer.

How long before you picked it up was it manufactured? Check the date on the side of the tire.It should not have been sitting long enough to have flat spots on the tires.

 

["EZ"]

These are 19.5" tires correct? If so, you can balance them until you are blue in the face and will not get rid of the "shake" you describe. The tire is not seated evenly around the bead and it has a high spot as a result. OR when they mounted the tire and wheel they did not put the light spot on the tire with the heavy spot on the wheel as they should, OR the radial runout of the wheel or the tire is out of spec.

I used to sell about 3000 trucks per year with 19.5" tires on them. That's 18,000 tires per year. The problems with 19.5" tires would fill a book!!!

Let's narrow it down............do you feel the shaking in the steering wheel or in the drivers seat? Steering wheel, it's the front tires. Seat, it's the rear tires. If it's the rear tires then sometimes you can fix the issue by "clocking" the outside rear tire vs the inside rear tire. If the both have a "hop" to them you can put the high spots opposite from each other and it will cancel each other out. Jack up the rear end, put the RV in gear, and let the tires get up some speed. Watch the tires and see if they "hop" up and down. If so, the tires need to be re-mounted correctly on the wheel or the tire itself has a high spot in it and needs to be replaced. Or the wheel is out of round. Of course I highly recommend you do this with the assistance of a tire store with proper equipment.

Look for the ring around the tire at the bead. It should be evenly spaced around the lip of the wheel. If not, the tire isn't mounted on the wheel correctly. If it is, the radial runout of the wheel or the tire one is out of spec. If I remember correctly the radial runout is +/- 40 thousandths. Have the tire store use a radial runout gauge to check the tire/wheel. You may need a new wheel or a new tire. If the tire store you're using doesn't know how to use a radial runout gauge then find another tire store! Most Commercial Truck Tire stores are the best and will know what I'm talking about.

Good luck and I hope this helps.

 

["EZ"]

BTW...........radial tires rarely flat spot. The old bias ply tires from the 60's would but radial tires can sit for a very long time and not flat spot. This sounds like something a tire store would tell you that didn't want to have to do the work to find the real problem. And be ready, if the tire store didn't install the tires they are not going to warranty the "balance" of the tires even if it turns out to be something besides the balance making them hop up and down.