From the Manufacturer

If you are a hobbyist that enjoys R/C vehicles or an all out R/C racer or anywhere in between, this tool is a must for your toolbox. Our toe-in gauge allows you to do trackside checks of the toe angles without removing the wheels. Our gauge checks toe through the simple method of comparing the width of the wheels at the rear of the tire to the width of the wheels at the front of the tire. Our gauge is accurate to within one half of a degree per side and closer. This tool can also be used to check legal width of off-road buggies and trucks. The gauge comes with a second thumbscrew hole to check narrower vehicles such as sedans as well.