Mama's truck

Hello All! I am looking to replace crummy chromed 16" Lexus OEM wheels on my 2001 LX470 with either painted 16" or painted 18" Lexus OEM wheels. I have two questions to anyone with an opinion> 1)Is there a significant improvment in ride / stability with the 18" rims to offset the higher tire cost? 2) Was there more than one color of "gray" painted 16" factory rim for the 98-02 lx470? Thank you all for your time and consideration.