Guys, im wondering if i should replace my shocks,

the car is a 93, and i have no idea if the previous owner replaced the shocks.

anyways i think they need a replacement, because they seem to be very loose. like, ever little bump makes the body move downwards and the body hits the rear tires. even with like, a slight change of direction in the street going straight at about 40mph, puts geforce on my rear, and the body hits the tires.

i dont know if its because my tires are too close to the body, they are 40's in the rear, and 35's in the front. should i replace the tires to 35's or should i buy new shocks?

what does this problem sound like to u guys?