Lots of handy stuff here for techheads and wannabes like me,i like the tire size calculator,now i know why some people recommend 195/65/15 or 205/65/15 if you can squeeze them in,doesnt change your speedo as much as others,anyway have a look go on you know yule need it one day, http://www.csgnetwork.com/automotiveconverters.html😉
And I have made a few, the most complete being my excel dyno which will do all your tyre size calcs, gear ratio calcs, and of course acceleration calcs. Only prob is you need excel http://offroadvw.net/tech/calc.htm