Resurrecting the old thread. I have 2011 IS350 with 18in Bridgestone tires. I would like to replicate a cushy ride that my 2007 ES350 with 17in wheels has. Will 16in on IS get me a lot closer than 17in since I will be changing rims anyways?

 

16" wheels can fit an IS250, but will not clear IS350 brakes. You need 17" minimum for IS350 brakes and even then you need the correct barrel and spoke shape to clear.

When I wanted to run 16's on mine for ice racing, I had to downsize the front brakes.

Jeff