I get the same kind of in a boat wandering if you go over a another boats wave ( not that bad). This happen when I put my new wide soft tires on ask the the tire people about it said the tires were wide soft and flat across they would grip the road and follow any defect in the road. Don't know if I buy all of it but not that bad after 300-400 miles and did notice that the outer edges of the tires do have a little more radius now.
Ken