Front End Issues @ 45mph or higher

[HUMTECH]

How wide are the tires, A wider tire can have this effect on A highway which has ruts, the tire being wider than the rut is trying to track in the rut, but will move in and out as the tire does not fit the rut. If it does the same thing on A good(new) flat surface road you definatley have A front end issue, possibly the steering gear may have worn pitman shaft bearing or other issues. Usually when felt in steering wheel can be attributed to A separated tire or bent wheelor a balance issue which will be magnified by A higher than stock offset on the wheel.

[Hummie2]

How is your steering stabilizer?

Here is the description from the shop manual concerning wider wheels and scrub radius increases that can be caused by wider wheels:

Scrub Radius Description

Ideally, the scrub radius is as small as possible. Normally, the SAI angle and the centerline of the tire and the wheel intersect below the road surface, causing a positive scrub radius. With struts, the SAI angle is much larger than the long arm/short arm type of suspension. This allows the SAI angle to intersect the camber angle above the road surface, forming a negative scrub radius. The smaller the scrub radius, the better the directional stability. Installing aftermarket wheels that have additional offset will dramatically increase the scrub radius. The newly installed wheels may cause the centerline of the tires to move further away from the spindle. This will increase the scrub radius.
A large amount of scrub radius can cause severe shimmy after hitting a bump. Four-wheel drive vehicles with large tires use a steering damper to compensate for an increased scrub radius. Scrub radius is not directly measurable by the conventional methods. Scrub radius is projected geometrically by engineers during the design phase of the suspension.

[mikejr]

me thinks its a bad kanooter valve assembly.....

[Hummie2]

Tim...

It could also be possible that its not a steering problem. It could be driveline related. How are the rubber bushings that mount the front axle assy. to the frame/crossmembers? I believe you said before that you first noticed it when you came back from Moab, is it possible one of the axle rubber isolaters could have been damaged? Also check your control arms on the rear axle. I recently changed my rear ride height slightly and could feel a vibration in the front floor and steering wheel. I had to install a CV rear driveshaft to cure the vibration. Those driveline angles are only correct when the "D" height is within spec. If it is driveline related the vibration will kill a set of pinion bearings in a short time.
Bad bushings in the rear control arms will not only alter the driveline angles, but will make the truck road wander especially on accel/decell.

[timgco]

Dealer called with the standard reply. They're mud tires, they are gonna do that.

[HUMTECH]

Also try and find A tire shop that can road force balance the tires. Any wheel sizes 18" or larger we always recommend this. With A road force balance the tire and wheel get matched and then weight is added to balance the assembly.

[timgco]

Originally Posted by HUMTECH

Also try and find A tire shop that can road force balance the tires. Any wheel sizes 18" or larger we always recommend this. With A road force balance the tire and wheel get matched and then weight is added to balance the assembly.

Road force test was done twice now. And was good!

The issues just started doing this a week ago. The dealer is going to throw a set of stockers on there and see what happens.