ducatipaso.org

Gentlemen:
I have installed a Michelin Pilot Sport 120/70/16 on my 3.5"x 16" Strada front wheel and a Pirelli Diablo 140/70/16 on my 5"x16" Strada rear wheel: Nichols mounted them, no problem. I chose these tires after a long look at the specs of what was available because they were the closest dimensionally to the original Michelins.
I performed a tire break-in/test ride today on a 50 mile course I do once a week or so, and I can report that the difference from the new mounts and my 8-9 year old M59 and A59 Michelins was remarkable: so much smoother, (felt like a new suspension) and much stickier than the old rubber. The rear seems to favor quicker turns and fall over nicely. I went faster than before up and down Redwood Road and I would say this was a successful tire intervention.

I joined photobucket and followed the guide created here to share the phoptos of the process. Here goes with the codes:

Randy - Great news! Finally a plausible solution that rides well and does not degrade the appearance. Do you think the rear would mount equally well on a stock rim?
Dave

I am not sure if the 140/70 16 Pirelli Diablo will fit the stock rear rim, it's 5.5" wide right? That may just be too wide for that tire if this is the case. Someone will have to confirm the width and try the tire. I can only hope.
—Randy.

Nicely done, and beautiful rims. Since you have those lovely rims, I can understand the search for some good 16" rubber. The rest of the bike looks clean also. We should go for a ride together, since I'm not far from you in Fremont. Redwood road is lovely ride with a great rhythm to it.

Cheers, Phil

Thank you Phil! I would very much like to go on a ride with you. I am leading a ride from Montclair to Coralitos Saturday Sept. 18:

Part 1: http://maps.google.com/maps?f=d&source= ... 18109&z=10

Part 2: http://maps.google.com/maps?f=d&source= ... 18109&z=10

Part 3: http://maps.google.com/maps?f=d&source= ... 09055&z=11

Part 4: http://maps.google.com/maps?f=d&source= ... 09055&z=11

We start at Peets and end at my shop for a bbq. Please come if you can. Best, Randy

Is that rear tire a Pirelli Diablo SC 140/70-16 ?
If so, it`s a bad choice. Recommended rim size is 3.75" max (you can see that the sidewall is basically vertical on the 5.00" rim) but the most important is that the Pirelli SC has a speedindex P (150km/h max) and a LI (max load index) of 65 which corresponds to 290kg which is much less than what is required. Original tires should have had something like an LI of 71 (345kg). The bike already weighs 220kg fully fuelled and w/o rider !
At speeds above rated speed index LI decreases. If you`re above LI index the recommended top speed decreases.
Unless you`re lightweight and don`t drive fast I`d consider this model as potentially dangerous.
As I say, if that is this tire.

jm2c,

G.

PS: your rear wheel excenter is upside down

Yes, that's the tire I've put on for better or worse. I weigh 150 lbs and the bike is much lighter than stock with the Strada wheels and aftermarket exhaust cans. I generally keep my speed well under 90mph. I know I'm on the edge with this choice, but I had to give it a go and it fit right up. I've had other bikes with tires that exhibited vertical sidewalls when mounted to the wheel rims, so I'm unsure of a downside to that condition. I feel safe with my choice even though it's a scooter tire for a 3.75" rim. I still feel it's a better choice for me than a big, heavy cruiser tire or oversize touring tire. I suppose riding an obsolete 23 year old bike is cause for compromise. I did a 100 mile freeway ride today at 80mph and it felt and performed great. Thanks so much for your thoughts and concern!

Say, I know the execenters are upside down, and I thought about this a long time and I couldn't figure out the downside of this position. What do you think are the disadvantages or inadequacies of this? For some reason that I just could not diagnose, I was unable to get the tire aligned to the swingarm with the execenters down: my gaps left and right were about a 1/4" off. I was baffled. Thanks again for your help, time, and thoughts on the matter.

Best, Randy.

Hey Randy,
Considering the Marvic wheels weigh a bit less the bike with you on it will almost be at the max load of the tire. (I wonder if that will make it wear faster). So you shouldn`t ride with someone on the back unless you dawdle.
The general concern of a narrow tire on a wide rim is the tire contour. It will be pulled apart and have a less round shape. This can be seen very good on the side photo if your bike. Hence depending how much you lean down in a curve you`ll get to the tire`s edge faster.
Just be cautious.

Strange that the wheel won`t align. I can`t see no reason why it wouldn`t as there`s only one position to fit the excenters on the axle. The difference of having the axle on the bottom or top is the height of the rear of the bike. The lower you position it, the higher the rear will get, the steering head angle will get steeper and the steering should become quicker. Of course that`s all marginal but one should be able to feel a difference.

G.

this tyre buisness is a real headache

Thank you again Mr. G for your help and for your valuable input! I will remain cautious as I continue to evaluate the rear tire. I will try again to change the position of the execenters in the next few days. I'll loosen the axle nuts and pinch bolts and remove to chain and give it another go.

I think this tire headache is worth it: the Paso is such an interesting bike and fits me and my riding style too well to ever throw in the towel. I think together we will find the best solutions to all the foibles of ownership— so much expertise on this forum! You guys are a real blessing.

Randy,
Thanks for the invitation to ride, but I can't make the whole ride, as I am hosting a party at my house that day, but I may just roll up to your place for the start of the ride to show off the bike and see the other interesting bikes of your friends , do the first leg of the ride back to my house. I know all those roads well. Looks like a great day of riding.

As to the vertical side walls, I don't have a concern. I have 170 tire mounted on a 5.5 inch rim (17") and the side walls are vertical. Yes, it may affect the handling, but compared to what? If it works for your bike, then apparently, it works. The load ratings of tires these days has such a big safety margin, that I would not hesitate violating one or more of the specified ranges from time to time. Most consumer products have a safety margin of 2 or more any way. A 23 year old bike surely hasn't the safety margin on some of its components any longer. Those tires are the least of your worries.

Cheers, Phil

Phil, it would be so cool to see your Duc at the ride start up: let everyone else on their triumphs squirm a little. I'd be so pleased to meet up and buy you a cuppa. That would make my day very special. And thank you for your thoughts and views regarding the issues of older Ducatis. My first bike was a '68 BSA bitsa and then a '75 GT550, so i guess i'm used to things falling off or seizing up, etc. Thank goodness for riding buddies and cell phones! As far as rear tires go, I'll keep searching for the best choice. I pray the
16" wheel gets popular again.

one can not really compare a 140/70-16 on a 5" rim with a 170/60-17 on a 5,5". The 170 is still higher and with a rounder profile.

The rear doesn't look that far out does it! but the questions of speed rating and load index have been answered for me. I think the 140/70 is a scooter tyre, am I right? funny when you think of it. I had sliding adjusters fitted so I can have ZR rated rear rubber and correct load index, the engineers are local and reasonable price considering. My habit is a little illegal road racing now and then and the other day it was a dice with a 1200 Turbo, man that was a scary race at times. Way over the national limit and some mad cornering even a full front slide (just had to share this with you) Suzuki rider was full of the 'its a Turbo so I don't really try' and was hugging the white line round a right turn, I looked at the gap between said rider and the curb and thought, 'I could get a Bus through that gap', got a slightly sideways Paso through instead. I was that low I could see under the turbo's tank. The rest as they say is history, I went so fast along the usual road that I had this feeling that if I got the braking wrong I was going to have an almighty accident. Think I will avoid the area for a few weeks, who said the fast bikes are new?
Now about that 140/70, what sort of failure do we think can happen due to the wrong specification? Deformation of radius? Rapid and uneven wear? Exposure of the carcass due to minor rips in the rubber?

yikes! Racer X was that your video? zzzzzzzzzzzzzzzzzzzz.