Betterment occurs when a component that is damaged in the accident has a certain life span. For example, tires may only have a life of 40,000 miles. If the accident occurs at 30,000 miles, your insurance carrier only owes for the remaining 10,000 miles. Therefore, if the tire cost is $100, you would be charged $75 “betterment” – for making the component ‘better’. Other common components are batteries, struts, shocks, some suspension components and sometimes driveline components.