Is it possible to downgrade rim size? 20 to 19

[mindless1]

So it's not enough when more than one person mentions it, you need a mod to bring you to senses?

If you can't communicate, what is the point?

Ok, enough with this pointless bickering. I'm going to give you a "pointless" (i.e. zero point) warning to underscore my . . . point (Gawd, I crack myself up.)

Point is . . . cease and desist.

Perknose
Forum Director

 

[JCH13]

Yea, that must be why all those Audis and BMWs have 80 series tires and 13 inch wheels, right? I would agree with the *same* tire size a lighter wheel would theoretically have quicker response. However, the point of a low profile tire is to get quicker, more precise response due to less flex in the sidewall. So it is a trade-off between the less weight and less flex in the sidewall. As for your "feel" of better response with a higher aspect ratio tire, I wont argue with your subjective impressions, but that is certainly not what one would expect. I will accept you point about my incorrect use of 'wider' and 'narrower'. Obviously what I meant by "wider" is "lower aspect ratio", i.e. that the width is greater in relation to the height of the sidewall.

Things beyond sidewall height contribute to steering and suspension responsiveness. Namely unsprung mass and rotational inertia. As wheel diameter increases mass also increases, but not linearly. It's something between a quadratic and cubic relationship. A small loss in sidewall stiffness can be more than made up for in a significant wheel mass reduction at larger wheel sizes. This trade-off results in diminishing returns as wheel diameter gets smaller because of the mass-size relationship of the wheels and the size-stiffness relationship of the tire's sidewall. That's why they don't use 13in wheels with 80 aspect ratio tires (well, and so that they can fit properly-sized brakes and hubs too). It's also why they don't use 23in wheels with 20 aspect ratio tires.