I am pretty sure I know what it is but wanted to get y'all's opinion as well.

 

I drove from outside Challis to Kuna, ID yesterday. The first 55 miles was dirt and then the next 170 miles of pavement everything was smooth as butter. Speeds up to 80+ at short times but cruising (if you can call it that on mountain roads) at 55-70 for a lot of it. Came to a stop at the intersection of 17/55 and got onto 55 and noticed a bouncing that was the worst at 35-40 mph. It smoothed out a little by 55-60 but I didn't push it past 60.

 

There is no vibration below 30-35 and rpms have no effect (i.e. lug in a tall gear or 3K in a lower gear). 

 

I am thinking a tire might be delaminating but unsure. It is definitely on the rear axle area as I feel it more in my seat than my feet and nothing thru the steering wheel. The transfer case lever is moving laterally up to 1/2" at 35-40 mph. My 6yo was in the back seat and said she felt it behind her without prompting. I told her I thought we might have a bad tire and she said, yup its the back ones I can feel it bouncing. 

 

Pressures were good, tires weren't hot, but the drivers side rear is wearing a little funny. They are my KM2's and the soft lugs makes the outside lugs wear faster from cornering (not a BJ issue as my M608z's wear dead even). Now I noticed that there is contact on the tire between the lugs (they are nearly worn out anyhow). 

 

So.. thoughts? 

 

I am going to go have them checked today on a balance machine. 

Day got away from me but here are some dusk teasers.

So far I am liking the look and feel of this tire. They will get some back county abuse before too long.

These are the tires I'm considering for the future.  The larger diameter will make 5th gear much more useable around the suburbs.  Those are the LT255/80 17E's correct???

Yes they are. 

 

There are currently only 2 tires made in LT255/80R17. These S/T Maxx's and the BFG KM2's I just took off. 

How you liking the Lt255/80 17E Cooper ST MAXX's so far??

Day got away from me but here are some dusk teasers.

 

So far I am liking the look and feel of this tire. They will get some back county abuse before too long.

I have been running a set of ST MAXX tires for about 30k now and I have been very pleased. They are a little bit more noisy now than when new, but the ride quality is still great.  The only trouble I had was the first set I bought developed a dry rot crack around the bead after about 10k?? The dealer swapped me strait out, and I have had no issues with the second set.

I now have a bit of towing, empty, dirt, and loaded miles on the new tires and I LIKE them a lot!!!

I'll keep them on for a few months and then back to the 19.5's for the spring/summer. 

How about an update on these tires John.  Probably spring for these Spring/Summer this year.

I'm sneaking up on 80,000 miles on the Discoverer AT3's now.  About 650 miles to go.