Ricardo - the riding style and environment here is very different to what you experience in Europe.
Oh I'm sorry I never file my profile.. (this facebook log in is not the best idea)
I have been living in the USA for almost 30 years, 21 in san francisco, 6 in salt lake city and now in minneapolis (where my LT make more sense..)
when I was living in san francisco I paid my school housing in palo alto (got a scholarship for the school) working on bicycle shops, mostly building wheels since I can take the "work home"
but trust me riding bikes, making around $15 per hour is really hard, lucky me I became really good friends with Kari from CalBMW (rest in peace my dear Friend) and he kind of let me pick up stuff front their trash, like semi worn out brake pads and tons of tires..
this bike today has 362.000 miles on the original engine, Seven clutches plus one I made a mistake on it) original final drive with original bearings, shaft, three transmission and trust me always load it way more than recommended (LT weight if you count the load)
Many of us think absolutely nothing about covering more than 600 miles (960 km) in a day. The road surface is also different, even here when one goes from state to state. If you take these things into account, you might have some understanding of the questions. I, for one, prefers to err on the safe side, and changed my tires when it was only at 8,000+ miles, when I expected to ride more than 4,000+ miles on that trip. Typically, my tires lasts around 10,000 - 12,000 miles.
Oh My,,, the Dolomites on MT-80's i will really need to carry spare tires for a three day tour..
In the same theme of "Starving student" I was always running out of all the consumables, but before coming here I spend a few years working on helicopters and building small composite planes, well to the point, Sure On those types of machines you do service by the "Hours" (save the gasoline of the helo, bikes run great mix it half and half with pump gas) but a safety check up
override any previous work or paper work..
Yes with bikes you do learn over time to questimate how much a tire is going to last, along the years I accumulate ready build wheels (Mostly from trash wheels the shops refuse to fix) that i just need to walk down from my apartment and in a few minutes I'm ready for a "Change of attitude"
In short they are many things I don't really about (like washing the bike as fun as it maybe be) but i never mess with objects that can interfere with Steerings or the chain and sprockets and brakes and tires for obvious reasons..