I'm sure your logs are very accurate as to money spent per vehicle. But not so much when it comes to cost per mile. There is just no way. $300 for a rear tire. . . . I can get TWO tires for my Jeep and they last 50K miles. Brake pads last at least 50k miles on a car/truck.
Depending on which tyre I get, I get pretty good mileage. The old Michelin Pilot Road 2, I regularly got over 25000km (15000m) for a rear and 40,000km (25000m) for a front. This was on two TDMs as well so lighter bike although leaning over a lot further for fun in the corners.
My figures for the three bikes:
TDM #1: average over 15 years and 247,000km is 6.6c/km for fuel alone and 19.4c/km for everything.
TDM #2: average over 10 years and 61,000km is 7.0c/km for fuel (hotter tune) and 26.5c/km for everything.
S Tenere for the last two months…
10.4c/km for fuel and 62c/km for everything else (bits & bobs not including purchase price) for 5,100km
For comparison, 2001 F250 with 4.2 litre 6 cylinder motor ( not available in USA) over 65,000 km for 5 years is 21c/km for fuel and 49.7c/km for everything else which has included tyres and the horrendous registration fees charged in this state.