Rear tire wear

[socalledchad]

Getting ready to put new tires on..before I do I need to figure out what is going on here.....

This is my back passenger tire...it's a little lumpy around the outside edge...it wasn't like this 14000 miles ago when I got it and I didn't rotate....any thoughts what would cause this on the back?

Also I got some vibration around 75

 

[HillbillyJedi]

Assuming all of your suspension parts are in good shape, it's most likely cupping from lack of rotation. Occasionally wheels that are out of balance wear like this but not normally. Have you had the vibration for the entire 14k miles or since you noticed the tire was worn unevenly?

 

[soSincerious]

Usually you see cupping on the rear of a FWD vehicle that hasn't had the tires rotated. It's strange to see that on a driven axle.

One thing I have noticed is that my truck (and I'm assuming all coil sprung rear axle Rams) has a lot of rear toe, about 2 to 2.5 MM positive on each side. I was surprised to see it, but it's within spec which I found intriguing.

I would check your alignment and rear shocks. If one is blown out it may accelerate that kind of uneven wear.

And going forward, rotate your tires at least once every oil change, if not sooner every 5k.

 

[ExpressRules]

Inflation Issue (lack of)?

 

[RR7_905RAM]

Is it like that on both sides of the tire? If so probably under inflation.

It does look like cupping which usually indicates worn suspension.

 

[GoldDot]

What is the air pressure in that tire?

 

[Rustycowl69]

Usually you see cupping on the rear of a FWD vehicle that hasn't had the tires rotated. It's strange to see that on a driven axle.

One thing I have noticed is that my truck (and I'm assuming all coil sprung rear axle Rams) has a lot of rear toe, about 2 to 2.5 MM positive on each side. I was surprised to see it, but it's within spec which I found intriguing.

I would check your alignment and rear shocks. If one is blown out it may accelerate that kind of uneven wear.

And going forward, rotate your tires at least once every oil change, if not sooner every 5k.

I agree. I'm surprised you never felt a problem.
Photo posted is a great shot of a tire sidewall, but did very little to convey the type or extent of unusual wear problem.
Is this truck lowered or lifted? If so, maybe the axle has shifted sideways relative to the frame.

 

[socalledchad]

38psi. It's only on that rear side...no lift or lower...suspension seems fine...I'm at a loss