Each pair of letters below can be made into a common word by the addition of two letters. The new words will share a common property. Can you determine the added letters and the new words?

IC
UR
LS
OA
IL

HINT:
ON could be added to the list.

Answer:

Each of the new words begins and ends with the same letter:

KICK
AURA
ELSE
ROAR
TILT