I have 21" tall Super Swamper rear tires, to get more bottom end should i get a smaller front sprocket, or a larger one?

 

Making the front sprocket smaller will make your gearing lower, giving you a little more bottom end. Keep in mind though that every time you drop a tooth smaller on the front sprocket you lose about 5 mph of top speed (assuming the gearing was allowing you to wind out in high gear before the change)

 

Thanks, even with the taller tires it still gets up and goes. I'll just keep it with the stock gearing, because where I ride I need that top end in some places. thanks for the help.