I got tired of struggling to hold straightedges against my wheels while setting toe so I built a couple of tools.
With the counterweight on the bottom, it stays level when the wheels are turned to the sides or if the car is rolled. The uprights allow me to measure toe without the body interfering.
I use these "plates" made from 3/4 inch furniture grade plywood and two measuring tapes. Just set them up against the tires on any level surface and read the tape rulers. If I'm working alone I usually wrap some masking tape around the plates and tires to hold them in place. These are easy to make and I made them from scrap plywood, so there was no cost except a few minutes labor.