Those are the Honda Comstar alloy wheels. If you look closely at all the punch-stamped info on them you'll see both "tubeless" and "Do Not Disassemble". You should also see "Tubeless" on the tires' sidewall(s). The alloy wheels do not use nor need tubes and so there shouldn't be any in those tires.
I just did a motorcycle tire industry "analysis", learning/searching for new tires for my '82 CM450 which has the exact same wheels as yours. I looked at the websites of:
Avon (England)
Bridgestone (Japanese)
Continental (German)
Dunlop (American made)
Duro (Chinese)
Kenda (Chinese)
Heidenau (German)
IRC (Japanese?)
Metzeler (now Chinese owned)
Michelin (French)
Pirelli (now Chinese owned)
and
Shinko (acquired Yokohama, Japanese)
You won't find a rear sized 4.60x16 and when I did find a 3.50x18, it/they were ONLY for rear applications.
The "S" is a speed rating for "Good up to 112mph" and the "4PR" = 4 ply rating, or 4 plies of rubber.
I narrowed my choices down to the Dunlop D404 and Shinko 712, asked a couple of elder Honda guru experts here their opinions, and just bought the Shinko 712 tires 100/90-18 56H front and 130/90-16 67H rear, both with "H" speed ratings (130mph), 4 plies of rubber, the 56 & 67 being Load Index ratings which are plenty for our 400/450cc motorbikes with their 810-pound GVWR (the bikes weigh ~420 lbs with a full tank of gas, add a 200 Lb driver and sometimes a ~130 lb passenger, a little gear, verify 28 psi of air in the front and back (unless with passenger, the rear gets 36 psi) and you're good to go.