Bad gas mileage

The tires a quite a bit taller not sure how much I filled it up Sunday and I have 155 miles on it now.And I was very close to empty.So in the morning when I go to school I will fill it up.

I held 14.3 gallons when I put gas in Sunday (not completely empty).I have ran 155 miles on this tank and am almost empty.

I have been using my dads GPS for the last couple of days and after the speedo reads 155 the GPS (garmin) my speedo is 2-3 miles off.