I have 2 65 Darts and 15x6 are as big as you will fit with stock tubs. If you can adjust the back spacing, I have 2 brand new 15x7 and 2 brand new 15x8 OEM steel wheels. I paid Classics $112/each for and will give you a deal and ship them to you.
Thanks for the heads up on the wheel size. To be up front, this 65 is my dream car ad I had the Dart GT Charger back in '71. So with that said, I am choosing to go with some nice looking wheels. I thank you for your time and input. Best. Old Dart 66.
