wondering steering

[bjarp]

I just purchased a 2005 swb srw 2500 4X4 with auto transmission. The truck had 79,000 miles on it. When I bought it the truck had 305/70/17 tires on the factory alloy wheels. The tires were worn out and I thought they were to big. The truck drove fine except for balance problems on the worn tires. I replaced them with 285/70/17 AT tires and had the front end aligned. The shop said that the ball joints were worn so I had them all 4 replaced at the same time I put the tires on. Now the truck feels like you have to constantly drive it. It will wonder on the road causing you to have to constantly correct the steering. Is there something on the tow setting that could be wrong or does anyone have any ideas? The shop said that they have seen other Dodge trucks do this and suggested that the steering box may have some wear. I dont buy that because it drove better with the old tires than it does now.