2004 Dodge Dakota Tires or Transmission?

Our truck has regular tires, replaced all 4 within the past year, the last 2 went on in March. All of a sudden my truck is feeling and sounding like we have off-road tires, that's the best way to describe it. My husband is concerned this may be a transmission not the tires. We have a trailer that he tows behind the truck frequently, he used it this weekend when the sound started, but the load was not particularly heavy, there was barely anything on it.