What is the performance advantage of a 16" tire/wheel vs. a 17" tire/wheel?

Seems like a combo of a small weight savings and a more compliant ride due to a taller sidewall, if you keep the overall tire diameter the same.

Is there a decrease or increase in cornering feel? Less positive turn in with a 16"? Any other benefits or compromises?

 

There's not much difference really. It all depends on which you buy. The big thing with smaller wheels are weight savings. The lighter the wheel and tire the less unsprung weight there is on the suspension giving a smoother ride as the suspension doesn't have to work as hard. Using a smaller diameter wheel saves wheel weight but depending on tire selection you can make up for that savings with a net loss due to heavier tires.

Tires with a taller side wall also tend to have a smoother ride as there is more rubber to give.

One last thing to consider is that larger wheels allow for fitment of oversided break kits as the calipers and disc need room to clear.

On your question about turning, that's more a function of overall tire diameter, tire width, and backspacing on the wheel. It's the tire itself that will limit your turning radius as it will be what rubs, not the wheel.

 

The 16's are almost always lighter...and this improves fuel economy, and acceleration....the ride is a bit better, and less blown tires and rim dammage (and strut tower deformations) from potholes and other things like raised manhole covers in construction areas, etc. The differance in sidewall height between stock 16's and 17's is pretty minor, and in the same width, the handling should be pretty close...but many 17' rims are wider...and this can help you get a wider tire, for more grip. In 16's in the oem size, tire selection is kinda limited, but there are 2 very common 16' sizes that are VERY close to the oem diameter, so there are actually 3 sizes to choose from, while keeping the speedo pretty accurate.
Most 17 rim/tire combo's are for looks....but the weight can be a big negative. Good, light 17' rims...2 or 3 piece rims, are very $$$.

 

PS...
When I have my light weight 15's on snows on my gen1 mini, the lighter weight rims/tires help the car be more nimble, and gives the steering a much more playful, light feel...the reaso. My auto x folks use 15's...handling differance is not as much as one might think....heck 90% of drivers cannot push a mini to it limits on a decent set of tires, so the DRIVER is usually the limiting factor.

 

I have some light weight 17s I am trying to part with with brand ne tires.

 

Car and Driver had an article on this a few years ago with the same tire and wheel in different sizes from 15 to 19 inches. The differences between sizes didn't amount to much, so it really came down to personal preference.

Link: http://www.caranddriver.com/features...d-tires-tested

I stick with 16s in summer and 15s in winter, just to help deal with the pot holes where I live.