So Andy and other experts. No one so far has discussed the consequences/impact of greater height, actually diameter, of the 120 vs. 110 rear tire on.....handling, braking, safety,etc. If the 120 has a pointier profile [being "pinched" by narrow rim], than the 110, what is the seat-of-pants difference?
It is going to be very hard to get quantifiable data from the oversize tire crowd. The "effects" are much more pronounced from the psychological side of the brain rather the objective data, analytical side. It is amazing how much the "seat-of-the-pants" data is conditioned by the human brain. There are too many re-calibrating factors between the two areas of the body. This is no insult, this is human psychology.
Personally, I'll take engineering data and/or track times over statements like; "This new oversize tire feels way better than the age-hardened, worn out, squared off, stock sized tire, on my low speed drive to the corner store, over patched or resurfaced roads of unknown composition with unknown substances on them, compared to when I last drove this bike 4 months ago."
Also, how do you take into account the skill of the rider? If he actually tests the limits of traction, the consequences of exceeding it are costly, vintage parts mangled, if not rider injuries. And, then if it was an on-the-street-failure, was it really the tire? Was the bike set up correctly, or a mismatch of the tire rubber compound to that particular road composition?
Given the road, machine, and human variables, if a rider looks at his bike with a wider tire, and then thinks he must have more traction, he may well simply ride it more aggressively, possibly nearer to the limits of traction. How do you find the actual limits of each tire size? The average rider doesn't really want to know. He just wants the performance edge beyond his needs. Most seem to be happy with a psychological "advantage". It's really only the racers that find the performance advantages in tires. And these change from track to track.
If you "need" maximum traction you will be replacing tires very often as the tire rubber composition changes (outgasses) with time, use, and heat cycles.
If you "need" a wide tire. Get one. Any new tire that fits onto your bike is better than your old one.
Personally, engineers are more likely to recommend a tire for scientifically supported reasons. Salesmen will recommend a tire where they can make a profit. Bigger tires usually have more profit in them than smaller ones. There is an amazing amount of mythos that goes along with wider tires. Especially for a bike technology over 25 years old.
Cheers,
I'm sure someone feels insulted here, but that wasn't an intent. If anything, it's a plea for objectivity and meaningfull data.
