Second Gen Tundra Fuel Capacity

I recently bought a 2011 Tundra Crew Max 4X4 Platinum and I've got some confusion on the fuel tank capacity. The owners manual and a quick google search show the tank should hold 26.4 gallons of fuel. Recently while traveling through the mountains I had to stretch the fuel range to make it to a station. When I pulled in the gauge was showing empty and the "distance to empty" was showing less than 5 miles. When I filled up the truck only took 20.5 gallons of fuel. I calculate my mileage manually and it is pretty close to what the truck is reading (~15.5 mpg). I've repeated this test running the gauge down to empty and each time I'm only able to put in about 20 gallons of fuel. It seems to me that the truck's fuel gauge is showing empty with 5+ gallons of fuel left in the tank. Was wondering if I'm missing something or if anyone else has run in to this as well.

Thanks

 

It has a 5 gallon reserve

 

My 4Runner was the same way. Technically the gas tank on your tundra holds 26 gallons, but the fuel gauge is calibrated to show empty and zero miles to empty at only ~20 gallons i guess. This gives people a built in safety factor of 5 or so gallons.

 

Common question, yes .

It has also been mentioned the reserve is needed to keep pump submerged in tank for cooling purposes.