FWIW, there is a lot of conflicting info on the web about this stuff, and this article is no exception and doesn't clarify anything.
i.e.:
Barry's Tire Tech
says larger and wider is better RR.
Quote:
Originally Posted by sheepdog 44
The benefits:
Taller gearing when converting from a smaller diameter tire
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in a properly geared system this would be wasteful since the gearing from the engine is always reduction, you would have to reduce it even more to compensate for the final increase.
Quote:
Originally Posted by NeilBlanchard
The geometry of a larger diameter tire means that the "wedge" formed by the tire at the road surface has a mechanical advantage to lift the tire over the bumps in the surface.
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I don't think that is it, they aren't testing on a washboard, and higher psi means you have to lift the entire wheel with every bump instead of deforming around it.
Like I said, lots of conflicting info, starting to think that tire/road dynamics are a lot like aerodynamics, you HAVE TO TEST to know if changes are good or bad (and you have to share the results IN A MEANINGFUL WAY).
Even the impetus for this very tire, the deltawing racer, is not a fan of larger diameter:
"“The front also has 15-inch rims for brake discs,” says Marshall. “Rim size is all about getting brake discs in. Clearly with race cars, it’s not like road cars, where the bigger the rim, the better for some people. It carries a lot of inertia with it. Big rims aren’t necessarily good for performance. You get the rim big enough to fit your brake package.”"
Tall, thin, FAST tires - Article - Modern Tire Dealer
Case and point, the tires are not 20" tall, if bigger=better.