We are starting a new class at our race track v6 front wheel drive
was woundering if the bolt pattern is the same between 15inch 16inch
for the buick regal -lumina-monti-carlo-pontiac grand prix

I think you'll find the bolt pattern is all the same, but there will be offset differences between FWD and RWD.

as long as the regals and monte carlos are late model FWD versions, then everything will be the same. In fact, all of those cars are actually built on the same W-Body chassis.