Absolutely correct. You can get tire bead sealer at an auto supply like NAPA.
Make up a solution of dish soap 1 part to 3 or 4 parts of water and brush it around the rims. With the tire under pressure, the bubbles will appear,but not right away. Give it some time and air it up a little strong to 15 or 20 PSI and the leaks will show up.
With all the aluminum wheels [just give me steel,please] on autos these days,sealing a tire with bead sealer is a skill worth learning.