I think I was thinking of it backwards. What you are saying makes sense. If you put a skinnier thre on a wider wheel, that should decrease sidewall deflection, right? You would think it would increase aerodynamics too. Thank you for the extra explanation.
I'm not sure I can even guess what would happen, with regards to fuel economy, for a narrower tire on a wider wheel. Gut feeling tells me that the mismatched tire/wheel width idea is barking up the wrong tree no matter how you do it, but I'd be interested in thoughts on what practical effect it might have.
Always appreciate your input. Again the tire thing is down the road a ways. Ill be sure to post my findings and some numbers at that point. Id like to get back into the previous idea of how many HP I need to build a high mileage town car. Is it ok to coninue this thead here or should I start a new one in the modding section?