I'm with Longgone. Back in the mid-60s, we used adapters to put GM wheels on large bolt pattern VWs. The adapter let us accomplish the objective, but...
The adapter moves the wheel toward the wheel well opening. Looks cool, but...
When the wheel was moved out, 1. it changed the camber, especially in the rear, accelerating wear on the inside edge of the tire. 2. the steering became more like a pedal car, stiff off center and then, whoof, you're hanging on to keep it from turning sharper. 3. Blowouts tended to throw the tire off the rim (caused by #1), especially up front.
For these reasons, I would not recommend adapters for street use. I can't imagine any competition sanctioning body to allow them, either.