1997 Honda Accord ex

Is this with brakes on that it shakes or is it just when you reach that speed? Just as a quick consideration, have you driven in snow or mud lately? A thorough washing of the wheels on both side of the rim should clean the deposits off and the car should handle better. Mud and snow can make the car seem like the tires are out of balance and this usually will manifest itself at the speeds you mention or there abouts.