Variable in for loop definition, is it possible?

I’d love to be able to use a variable to define the variable in a for loop. Surely, it’s possible? Here’s the basic syntax I’m trying:

	var r = q + 1;
		for (var i=r; i<8; i++){} {

Notice I’m trying to set i equal to r.

Do I need brackets, quotes, some other fancy formating?