Tire Size Calculator 2.0 is a major upgrade over the current tire Size Calculator available for webOS. Tire Size Calc 2.0 will calculate your speedometer difference (at 60 mph) as well as vehicle clearance given two different sizes of tires. Tire Size Calc 2.0 allows you to enter any values you want for the tire width/aspect ratio and wheel size. It also allows you to enter the size in Inches as well as mm. Another new feature is the ability to calculate your overall gear ratio and then use that along with your tire sizes to calculate your RPMs at 60 mph. Included in the menu are options that allow you to call 'AAA' if you need roadside assistance, search for either tire size on tirerack.com, find nearby tire shops, and there is a page that contains a wealth of information about tires in general.