Haven't seen any posts link DW and scrub radius together like this: "The smaller the scrub radius, the better the directional stability. Scrub radius is dramatically increased when aftermarket wheels and tires, that have additional offset, are installed. They may cause the centerline of the tires to move further away from the spindle. This will increase the scrub radius, which in turn reduces the directional stability. <font color="red"> A large amount of scrub radius can cause severe shimmy after hitting a bump. </font> That is why four-wheel drive vehicles with large tires use a steering damper to compensate for an increase scrub radius." Might be worth looking into, if nothing else we now know why the stock trucks have a steering damper.