I would prefer a tyre company to make tires with a 15" bead dia on the outside With 17"/ 18"/ 20" or whatever on the inside bead. This would give the external classic look but the brake clearance & low sidewall advantages on the inner. Since the inner sidewall carrys a larger percentage of the lateral load in a corner the handling advantages would be there and tyre fitment to the rims would be simpler since you would only have to fit the 15" side as the 17/18 inner would drop over the 15" side of the rim. There would be slight advantage in less likelihood of sidewall damage in driving over kerbs etc as well.
Of course no one will be able to patent it or claim intellectual property etc of the idea now as I have posted it here on a public forum!!!
Jac Mac