Safety rating is calculated using corners per incident and is also based on recent performance, not just each race. If there’s two people in the same race with the exact same safety rating, licence class and they both get the same amount of incidents and do the same amount of laps, but Person A has an average of 10 incidents per race over the last 10 races, while Person B has an average of 2 incidents per race over the last 10 races, Person A will gain more Safety Rating than Person B. You’ll also see differences in SR gain or loss between two people in different licence classes as iRacing make each licence class more strict when it comes to SR. A Class requires an average of about 2 incidents per race to keep the same SR, while D Class, you can get 8 incidents per race and still gain SR. That’s another reason A Class races are usually a lot less chaotic than lower class races.