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. 

Pretty common for our vehicles driving gravel roads all the time if they are really dry and dusty, rims fill up with dust and when stopped all the dust dirt falls to one side of the rim and then causes a vibration, same goes when we get a lot of rain and drive gravel, surprising how much dirt builds up in the rim, I just wash out the inside of the rims and good to go again in most cases.

I would tend to agree with Bill I would check the wheels for build up first. Then check the balance afterwards. Thing is it takes so little of out of center weight to create a wobble. Especially will large wheels and tires.

any mud recently?  

The wheels were clean, and had operated for 170 miles at high speeds that day.

The balance check is really to isolate the one that likely has a delam or chord failure.

The wheels were clean, and had operated for 170 miles at high speeds that day.

The balance check is really to isolate the one that likely has a delam or chord failure.

 

 

........................or a lost weight or simply time for a rebalance......................

When I picked up my used (former lease) Avenger just over a year ago, it drove perfect.  Within a few months it felt like I had a slight out of balance tire...  slight & not consistant.   Recently, I had a more serious shimmy in the steering wheel (flat was on the rear).  They found a broken belt on the driver's front.  They offered to rotate the tires to put it on the rear where it would be felt less until I got them replaced.   

So I'm shopping tires now.  

IMHO, the current trend to low sidewall tires is bad for consumers.  Wife has gone through a lot of busted tires on her Hundai Accent.  She had been buying from the dealer but they would not warentee the tires, not even the ones she bought after the OEM failed so she went somewhere they WOULD give road hazzard.      

Turns out there was a broken chord in the drivers rear. The put the spare (5th tire of the same on) and away I went with a smooth driving truck. 

 

A set of 4 new Cooper S/T Maxx will go on tomorrow in 255/80R17.

 

That makes 2 chords damaged within 1,000 miles of each other (thou 11 months apart) on the same stretch of road. I guess the tires are worn out. 

John I though you had industrial truck tires now?

I do. I run those for most of the year and run the 17's during hunting season. 

 

This was on my 255/80R17 BFG KM2's. They are 6 years old and down to about 5/32" so it was replacement time. I put so few miles on them these days (~1000-1300/yr) that I was hoping to eek one more season out of them... oh well. 

1000 to 1300 a year. I have never had anything to drive that little. Maybe in 3 1/2 years after I retire. If I get to that low a mileage Mike might beat me back from the moon.

1000 to 1300 a year. I have never had anything to drive that little. Maybe in 3 1/2 years after I retire. If I get to that low a mileage Mike might beat me back from the moon.

That's just on those tires...

Thats actually a little low now that I really think about it I think 2K is a better average. They are 6 years old and have 22K on them (5 tire rotation) and I ran them full time the first year.

That's just on those tires...

Thats actually a little low now that I really think about it I think 2K is a better average. They are 6 years old and have 22K on them (5 tire rotation) and I ran them full time the first year.

Guess I saw the 1300 and forgot about the other tires.

i was gonna say and impact bruise. or maybe lost a shock bolt.

the quality of BFG tires went to pot a few years back. i hope they got it fixed.

Glad to see you getting Coopers. Made in the USA!!!

BFG was the only option for 255/80R17 in 2009.

 

All in all, despite only getting 22K miles out of 5 of them, they held up to some serious abuse. The road we elk hunt on is no joke and that was their main purpose in life starting in 2011. But when the Coopers came out last year I set my sights on them.

 

Dad showed up to elk camp with a set of brand new KM2's in 255/80R17 so we will have a decent comparison. The KM2's saved his bacon more than once in deep snow with a horse trailer an no chains, so hopefully the S/T Maxx's do just as well.

I am on my second set of Cooper ATP's. First set did real well, hope these do too.

how many miles did you get outa your first set?

how many miles did you get outa your first set?

65k on the first set. That matches my best on Micheline LTX's, 65k

The new tires  are on and the truck is very smooth and quiet.

 

I had couteract balance beads put in, same as my 19.5's, and the tires don't feel like an aggressive tread at all up to 75.

 

The new tires have a date stamp of 3315 which means they are only about 7 weeks out of manufacturing which isn't bad at all.

The new tires  are on and the truck is very smooth and quiet.

 

I had couteract balance beads put in, same as my 19.5's, and the tires don't feel like an aggressive tread at all up to 75.

 

The new tires have a date stamp of 3315 which means they are only about 7 weeks out of manufacturing which isn't bad at all.

I've been looking at the cooper S/T maxx for my next set of tires, I have Nitto terra grapplers on now and with only 10k miles on them they are at 50% tread, so I'll probably be buying tires sometime next summer.