The higher the load the more the tire will heat up. Specially in combination with a lower tire pressure (0,4-0,5bar is already enough) this can lead to a damage in the tire fabric. There won`t be any signs of that which can be seen. But in the longrun or on long rides this can lead to the thread pattern to come off and/or the tire to blow out. Wear is probably also higher. Problems can already occur if the weight of the vehicle corresponds with the tires LI index and are more likely if you exceed it.
One should be aware of this and ride accordingly if you choose such tires no matter if there is still some safety buffer.

I checked on the tires to verify their load ratings anf their model numbers just to make sure they were both accurately reported in this thread and the results are:

front is: Michelin Pilot Sport 120/70 16 MC 57 H max load 230 kg/507 lbs
rear is: Pirelli Diablo 140/70 16 MC 65 P max load 290 kg/639 lbs

Thank you again all for your comments and feedback.

why you did not consider this: SPORT DEMON 150 70 16 68S for the rear rim?

it's a little bit larger...

That tire is, in my experience, unavailable through any retailer in the U.S. or at least I've never been able to find it. I am unable to find that size available in any tire. It is an intriguing size though...

Thanks for you thoughts! Best, Randy.

the pirelli SPORT DEMON 150 70 16 68S in Italy is available for 80 €

I know that someone in Italy is using that tyre on paso rim

that sounds like a reasonably priced option. does it involve any mods to the bike at all?

that one should fit w/o any mods. It`s also a scooter tire, recommended for 4.00x16" rims.
(speedindex S: 180km/h, Loadindex 68: 315kg).
It`s a very uncommon size that exists from Pirelli, Maxxis or Dunlop (D404 but I think these were discontinued)

For the ones who didn`t see it. For the P750 & 906 Ducati Germany recently issued a document of compliance for a 130/70+150/80 Avon tire combination. It will require lifting the front fender and probably a longer chain.
http://www.box.net/shared/gq6hrzi9s4

Did you have to do anything to the chain or sprocket?

Thanks. I just had my swing arm modified by Morgan Machine in SF. I installed a 160-80-16. The tire will work but I need to get a different rear sprocket--like a 38 tooth. I tried making the chain longer, but that didn't work. I think the solution is a smaller sprocket. By the way, I am looking for the large allen screws that fit the side body work to the fairing. I have two parts bikes but those screws are long gone. Thanks. Richard.

I installed a 150/80 rear tire on my 750. Only modifications I had to do were a longer chain (108 links instead of 106) in order to get the tire rear enough. (Otherwise the tire does not have enough room to rotate.)
And a larger rear sprocket (40 teeth instead of 38), in order to get the chain tight enough (with the 38 tooth sprocket there´s not enough adjustment range to tighten the chain).

Pretty simple anyways, didn´t have to do any irreversible changes to the bike.

Regarding how the tyre can fail, I had an experience with a z650 in France about a decade ago.

Went touring on a bike I had just purchased from a courier who was running it on cheap tyres.

cruising at about 150kph with a passenger and luggage the tyre staretd to delaminate (tread bulging and unsticking from the carcas). Eventually the bike would wobble (to the degree that I could not guide it at all) at anything above 30kph. Did the lakt few km below that speed to get back to the UK as I was a student with no money or no time to get a tyre in France.

At a guess I would say it is unlikely that you would have an instantaneous and catostrophic deflation, but the bike could become seriously unstable at speed which may result in a similar outcome.

drove to the tire dealers today and got a bridgestone 130/70-16" fitted on my Paso.

Had to remove the front fender for now, got to put some spacers and longer bolts so that the wheel has enough room to rotate. This I had suspected so no news to anyone.

BUT!

What I did not expect was that the tire contacts with the fairings at the bottom of the side fairings (you know the front-low edge right under the front cylinder) even in the smallest bumps or if you turn the wheel too much.

Has anyone else had the same problem?

As I recall, someone said on this forum that you would not have to mutilate (modify) the fairings when fitted a different then 130/60 tire.

so where did I go wrong?