Hello Paso problem solving brothers and sisters!
I have been a lurker here, taking tips and learning; and many (9) years ago I bought the Haynes Weber manual, which I studied into some effective understanding, thus avoiding a Mikuni conversion. I also successfully did Bauke's electrical system relay mod.

I downloaded (Gerhard's?) shop manual, and performed various other important mods made good by your collective benevolence and suggestions (rear shock recharge, front fork reseal, brake pad/disk renewal, fairing nut bushings, tips on repairing cracks to fiberglass, airbox mods, carb emulsion and ventri tube swaps, clutch throw-out bearing lube, etc.).
My lovely Paso (blue; can I post a pic?) has been in the barn for a few years as I have been recovering from a back surgery. Lately I have too many commitments/hobbies, so the 906 has been inactive. But, as rust never sleeps, I have been worried over tire replacement issues. I just found this thread.
Most reasonable people in my life advise me that I must sell my Paso. I love this bike and I won't sell it. I have been doing a cost/benefit analysis, and I do not want to "externalize" the costs. So, what should I do?
I must say, IMHO, that the Wild Colonial Boy has the most measured approach to these rear tire issues. Machining and spacing ( and maybe a longer chain/extra teeth on the back cog) looks like a great and responsible way to go. I can do this in my shop. But...
I also like the idea (props to xchopper and ukizook!) of gently sanding off some of the outermost chainside lip of my (future) tire. I would do this while carefully measuring the thickness of the sanded area with an elliptical caliper, like those used by bowl makers on wood lathes. I am not a back-tire rider who must scrape a peg every now and then (even while I wish I was that rider!). I am a commuter/tourer. If I need to scrape a peg, I'll borrow my younger brother's CB750. I would never be able to wear off a proportionately even elliptical 5mm from a rear Paso 906 tire, so I am going to take this belt sander path to the 906 rear tire problem solution.
I also agree with the idea (I apologize for having forgotten the names of the ducatipaso.org writers who championed this idea) that all tire combinations will offer something unique. The best approach is to carefully discover and learn the limits of those combinations, and live with the results or move on to some new tire combinations. I do this, while I reflect on my budget limitations and ethical/safety commitments. I am a mostly center line rider. That is to say that I believe that I keep the rear tire on its center line 75% of the time.
FWIW, I am not an apolitical person. I believe that language barriers and electronic media/cultural differences and expectations will always condemn me to misunderstand my friends who exist in other language groups and national/ethnic identities; so I always seek more dialog in those inevitable moments of misunderstanding. BTW, I love my country and I vote my conscience. I also have a deep respect for dissent and reasoned debate. Democracy is an agonistic process: sort of like Paso ownership.
My good fortune: in my home state of Maryland, USA, my 1990 Paso 906 qualifies as an antique bike. And, as such, it is exempt from detailed inspections of tires. So, here I am. Thanks for your time!
Yours in Paso,
Michael
ukizook wrote:G, All the tyres you buy today usually have about 6mill tread depth when new, the rubber extends beyond the thinner sidewalls. We just had a pad on an angle grinder and was very gentle with the pressure (or the clever ones borrowed someones tread cutters and hot knife
I doubt any Paso rider would ride to the edges of a 180/60 profile tyre "not through any lack of ability of rider or bike"

but I see many 180 tyres with over 5 mill wear on the very edge of them after a vigorous trackday. I know it's not quite as simple as this but imagine you had a brand new tyre and managed to (evenly )wear 5 mill of the entire tread. Apart from now having a nearly bald tyre everything else would still be fine.
Again this may not be the optimum fix and I for one chose C Boys fix with an old turned down sprocket as a spacer.
The only drawback of a 180 tyre that I see is the limited chain adjustment.
