[thstone]

Since the tire widths would stay the same, the only benefit is weight and the 16lbs that you might save is the same as two gallons of gas. In theory, there will be an improvement from the lower unsprung weight but I worry that it will be imperceptible in comparison to other variables.

If you are consistently within a tenth of a second of the being on the podium, then this might be worth it. It certainly won't hurt so you have nothing to lose but some money in the short run and chasing the podium is often a matter of optimizing several variables to get the needed aggregate result (meaning that picking up a tenth here and a tenth there all adds up eventually).