I cheat a little bit. First I assemble the suspension & make everything as square as I can. I make the mounting holes in the wheel backs slightly oversize with just a little bit of play. When I glue the wheels on I place all the tires on a piece of glass (flat surface) & use machinist V blocks pressed up to the wheels & eyeball the alignment from the top. Works every time & I always have all 4 on the ground.