The Longacre Toe Gauge is a simple, inexpensive, yet accurate way to measure toe-in/toe-out. It's even easy for one person to use alone. Simply scribe or mark a reference line around each tire* and line up the two pointers on the gauge with the lines on the rear of the tires. Note the measurement and repeat at the front of the tires. Subtract the front measurement from the rear, and the result is your total toe-in (a negative result indicates toe-out). The pointers are mounted to a telescoping tube with a graduated scale for easy measurements.
* The reference line doesn't even have to be centered on the tire, as long as it is parallel to the centerline of the tire. If you spin the tire and see only one line (as opposed to a spiral), you're set!