In any parallelogram, the diagonals bisect each other. This means that the point where the diagonals intersect, point \( R \), divides each diagonal into two equal segments.
Given that \( SU \) is equal to 11 inches, we can find the length of \( SR \) as follows:
Since \( R \) is the midpoint of \( SU \), the length of \( SR \) is half of \( SU \):
\[ SR = \frac{SU}{2} = \frac{11 \text{ inches}}{2} = 5.5 \text{ inches} \]
Thus, the length of \( SR \) is \( \boxed{5.5} \) inches.