Steering wheel vibration at 60-70mph after rotating tires

I recently (3 months ago) bought a 2010 dc Trd or (4.0l v6) manual. It came with duratracs (265/75/16) and a leveling kit (bilstein 5100s, aal). The tires supposedly have about 30000 miles on them. I bought the truck when it had about 25000 on the tires and last week rotated the tires front to back, not diagonally. I can't say whether the previous owner ever rotated them.

Now I'm finding that at 60-70 mph, the steering wheel vibrates strongly side to side, about half an inch in either direction. That is rotating half an inch, back and forth, relatively quickly. It does it somewhat intermittently, and I can't seem to find any variable that makes it do it other than speed. At 75, it doesn't happen (or it does so little it doesn't matter). The alignment seems fine, even when it does the vibrating. No bouncing, so I don't think the wheels are out of balance.

Could they just be worn really oddly because they weren't rotated? Is this something that will work itself out, or do I need to tires? They definitely show some wear, but I'd expect them to get at least another 5-10k miles. They have always been fairly loud, but are my first ATs so that might be normal. They don't seem to be much louder now than before I rotated them. I have about 7 hours of highway use on them since I rotated, and there seems to be not much change, but maybe it happens a little less frequently. I'm a bit worried because I'm driving Virginia-Colorado next week and really don't want to have any issues.

Any thoughts as to what might be causing this? Is this a duratrac problem? Should I just put them back like they were? New tires? Also, what pressure are people running these at? Could low/high pressure be causing this?

 

If they were out of balance on the back chances are you would not have noticed it.

 

First stop, balance all 4 wheels.

 

Balance to be sure.

 

I had the EXACT same problem. Got tires, everything was great. Got rims a few thousand miles later and rotated during install. Crazy vibes between 55-65 just like you describe. Had them balance again and again and again and again until finally they said I tire which was originally in the rear was a little messed up and wasn't balancing correctly. They said only way to fix it is to leave it in the back so I wouldn't notice it. A few thousand later my rear tires were WAY lower than the fronts so I was forced to rotate. Vibes came right back. I lived with it for about 1000-2000 miles until I got a nail in my tire. Took it to have it patched and asked them to rebalance that one bad tire in the front. They did and it all magically went away. So I have no clue what's going on but I have reason to believe that the offroading and abnormal wear on the tires had caused it to mess up that one tire and not balance properly sometimes. I suggest getting them all balanced. Also check for things stuck in the tread like small rocks or nails. Those can throw it off.

If a balance doesn't solve the problem, I recommend leaving the tire in the back because if you leave it in the front all those vibes will eventually cause abnormal and premature wear on other parts of the vehicle like wheel bearings and ball joints. Also tie rods and steering linkage is subject to wear and breakage. Those vibes aren't good especially when they are that bad.

 

@Poolstick: what wheels do you have, stock or aftermarket? Many aftermarket wheels require a plastic hubcentric ring to center correctly. The ring may have gotten destroyed/displaced when you rotated the tires.

Most places that do tire balancing can also determine if the tire is worn unevenly by visually looking at the tire.

Another possibility is a bent rim in the rear, now affecting steering in the front.

 

Have the stock Trd. Got them balanced yesterday afternoon and now all seems to be fine. Thanks everyone!