Why are so many people running 18” wheels?

[Full_of_fit]

Hello everybody,
Obviously, the title is my question. I am curious if people are using 18 inch wheels due to having more traction or beefier tires. Thank you for your help,
Ian

[SYT_Shadow]

I run the smallest wheel possible for more compliance.

I just got a set of 19s for winter wheels on the X5M. They barely clear th3 calipers, but happy to have something smaller than the winter 20" set.
For the summer setup, found a set of the very rare 20" to replace the 21s the car came with.

[M3SQRD]

18” wheels give you more compliance due to tires with taller sidewalls and weight savings over most 109” wheels. However, my 19” HRE R101LW, which have been used on track, are considerably lighter than my 18” setups but 18” wheels have slick race tire options.

[b_w.]

Better tire selection and ride quality.

[agentrnge]

~15-20 years ago there was a tirerack test on probably an e46 test car where they compared 17/18/19/maybe 20? inch wheels and otherwise same tire/tread size and width. the 18 performed the best for absolute max lateral as well as accel/decel traction, had better lap times. Just didn't "feel" fast on initial turn in. Will see if I can find that