Tire/ tube question

[RatTrap]

MY rat has US Indy Mags on the back and the tires
are 305/50 R15.

The drivers side started leaking down Sunday and was
flat on Wednesday. Stuck it in the wading pool and soaped
it up and had a stream of bubbles at the valve stem.
Took it to NTB this afternoon and they found it had a tube in it.

Anyone have any idea why this would be tubed? The skins
are BF Goodrich Euro T/A and look nearly new.

Also- I am having trouble finding a new tube this wide.
Any recommendations on where to find wide tubes?

 

[gassersgarage]

There are usually tubed if the hole that caused the tire to go flat in the first place was too big. You can order tubes from your local tire store.

 

[RatTrap]

Tires are new

Both rear tires appear to be new.
Both rims have tubes. The stems are
in the middle of the rim near the hub.

I thought maybe it was because the
tire height to width ratio was so low.