If you are stopping at an intersection with stop bars, you should stop before: you lose sight of the line your front wheel wells cross the line your front tires cross the line your front bumper crosses the line

Your front bumper crosses the line

Explanation:

Your front bumper crosses the line.

Assume you have a line Say as A on one hand and B on the other hand.

AB .

The vehicle stops at an intersection of wit stop bars that means that the vehicle crosses A when when it comes from the left and crosses B when it comes from the right. It happens when the front bumper crosses the line Alternative A and B is omitted as the tires are behind the bumper so when the bumper crosses the wheels also cross.

if they have a finite resultant