Since the Toyo tires have a larger aspect ratio, they will have a larger circumference. This in turn means that you will be going faster/farther than the speedometer/odometer indicate. I'm too lazy right now to look up the exact amount of difference, but it should not be too terribly significant.
BTW, switching between 15-16" tires is irrelevant since they will typically have different aspect ratios and/or widths to compensate.