a 25 tooth sprocket will fit on a 9 tooth driver
9 tooth driver
13t driver goes on a 33t sprocket
13 tooth front/ 40 tooth rear
41 tooth
Usually the sprocket is an inseparable part of the freewheel, and the size of the freewheel is determined by the hub.
It uses a 47 tooth sprocket.
First you need to be clear about what you're talking about.In regular Bike-speak, sprockets go at the rear, and chainrings/chainwheels go at the front.In BMX-speak, a sprocket goes at the front, and a driver goes at the rear.If you're speaking BMX, the most obvious difference is the size, the tooth count.For the same size driver, a bigger sprocket will make the bike slower off the start, but give it a higher top speed.For the same size driver, a smaller sprocket will make the bike quicker off the start, but give it a lower top speed.If you change the driver to match, start and top speed will remain the same, even with a smaller/bigger sprocket. A small sprocket will increase the ground clearance. Better if you're riding ramps as there's less risk of the sprocket/chain hitting the lip as you drop in. If you're not riding ramps, well, a smaller sprocket is still lighter, which is a kinda-sorta advantage. The downside is that the smaller they get, the faster they wear. And the chain wears too.
There isn't much need to discuss tooth size as such. The important things are which width of chain the sprocket is intended for and the tooth count. Tooth count decides which gear ratio you get.
you don't use a freewheel for a 23 tooth sprocket you need a cassette hub heres gear ratios for yaSprocketF/W or Cassette2282382592810301133123613391441154416
45 tooth rear
17 tooth front, 42 tooth rear, 110 link chain, size 530