Are 1.75 inch thick paving stones OK for a driveway

Yes if your sub is laid correctly. A porper base of bravel and compacted fines is needed in most locations, where are you?

Ballenger's question is a good one. If you live in a place that sees snow I would probably stay away from a paver driveway because shovels and snow blowers might keep getting snagged. Not to mention the freeze-thaw cycles would probably be rough too.