Will 17 inch tires and rims from a 2007 silverado fit on a 2000 silverado with 16 inch tires and rims will it screw up speedometer reading?

The Rims will fit as long as they are the same number of studs and puting 17 inch rims on will not screw up your speedo as long as the tires you use have the same outside diamiter. If they are the tires that came with the original 2007 silverado they will be the same outside diamiter as your 16" wheels and tires

You can also adjust for larger tires on the speedometer with a hypertech controller.