Bill Jurgenson wrote:Don't overlook that there is BIG difference between radial tires and diagonal tires. In the old days, it was common place to force big diagonal tires on narrow rims and it really did no much matter as long as the thing went on entirely. The contour of the tire remained round, more or less pinched but nevertheless round regardless.
Radial tires don't behave that way and that is why recommended rim sizes are important for modern belted tires. Mind you, there are a lot of diagonal tires still being sold for motorcycles. The BT45 is one prime example of a very good diagonal tire which is not oldfashioned.
As far as the Skorpion and SZR are concerned (and the similar age FZR400 which has the same 4" rear wheel), at the time of their introduction 160/50 was the smallest radial tire available.
As I posted way back, the prototype Skorpions had the TZ250 adjustable RSU fork and wheels : 3.00/17 and 3.50/17 and had a 130/ tire in back. The only reason for the last minute changes, done AFTER official dealer showing and testing, to the crummy Grimeca wheels and the larger size was the wish of a few executives to offer the Skorpion with sidecar; the Brembo wheels were no rated high enuf for the additional side load of sidecar use. The upstart of the while thing is threefold:
!) the Grimeca wheels were not cheaper;
2) the sidecar outfit was never weven announced let alone introduced, and
3)the Grimeca wheels are actually weaker than the Brembo as many many can attest who have had involuntary contact with railroad tracks , curbs, etc.
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Yup, radials are different than Bias tires. Haveing been involved in tire development with Dunlop, B.F. Goorich, Michelin, Otsu and Kumho tires, while employed by General Motors North American Opperations, Milford Michigan and also Roush Technoligies, Allen Patk Michigan, with Ford's SVT program, and some tire testing with a few divisional motorcycle teams in WERRA, I am aware of this and what too narrow or too wide of a wheel will do to a radial tire. I've seen the narrow wheel, wide tire, and vice-a-versa, come apart at 300 FPS slow motion. It is facinating to see how the forces of load distorts the tire as it looses contact by buckeling, the heat generated and the destructive force goes up exponintally to the load generated, to the point of destruction. Yes car tires are different than bike tires. But theroy and construction remain.
Point... The tire I chose, I inspected first, The Raven has a sturdy carcuss and tread cap. It should and does hold it's shape, The Raven is a curved profile and not rounded, as this profile on a slightly narrow wheel becomes slightly rounded, as the photos show. it works, gives ME the compliant ride and footprint I want and is very stable. As stated, if the 4" wheel was far too narrow and caused an issue of profile or stabillity, I would not use it.
Every thing is a compromise and I like the 1 size up( 1.25 on the MZ?) compromise on my daily street bike for ride quallity and wheel protection. I would most likely not go that route on a performance/race bike(maybe on Neruenburg, its awefully rough) and have never used anything more than 1 size up. It's a compromise I like.
Well done lecturing.... OFF to die a firey DEATH!!!! lol
