IMS 18L /4.7 gallon true capacity

I was looking for this information and couldn't find anything.

I took a cold winter spin on my wr250r/x to burn the last of the fuel out of my IMS 18L tank. I took a rotopax along incase I ran out. I wanted to see how much fuel this tank could take.
I sputtered my way into the gas station nearly empty.
Pretty well filled to the brim, the tank took 19.3L... I was pretty surprised. Thats closer to 5.1 gallons.

Pretty much all of them are like that; mine takes 5.2 gallons.