Tyres will be more than 400 surely? Also disc and pads are way more also. Isnt 20mpg a bit optimistic aswell?
Read it carefully - these figures are my rough guesstimates of annualised running costs over five years, doing 5,000 miles a year, and assuming the pads, discs & tires are good for 15,000 miles. Which is maybe a bit optimistic for the rubber, but this isn't an exercise in precision cost calcuation.
Did you not expect to be challenged, people love to have their say!