I have a toy car I am using to walk my dog. The toy car weighs about 15 pounds while my dog weighs about 20 pounds, ocassionally my dog will pull. The wheels on the toy car are 4-inches Diameter and 2-inches width. The tires are made of rubber and have a chevron type pattern on them. How much more weight would I have to add to my toy car to ensure my dog will not run off dragging the car with it? Also how much traction is being produced by the tired? Please provide all equations, steps and value refrences in your answer. Please give different answers for if you are on pavement or if you are on grass