I'm sorry, but not only is 4 wheel touching rule dumb, but enforcing it does NOTHING. The people that know how to build fast cars, or care enough to go to sites like this to LEARN how, will still be the top cars.
So if someone comes here and learns about a 3 wheel rail runner....making him have 4 touching isn't going to give a prayer of catching him to the people who don't even start building their cars until 2 nights before the race.
Now...if the 3 wheel touching rule is dumb, then trying to check for and enforce canting makes Forrest Gump look like a pure genius.
Seriously....if you use the slots and just stick the axles in there, then no matter how hard you try, you absolutely 100% cannot get them in perfectly straight....and that's ASSuming the block isn't warped and having all 4 straight in would actually make them all be in alignment in the first place.
Why the hell would you do this? It will be VERY subjective if you do something as dumb as "shining a light and trying to see if any gets through to tell if the wheels are flat".
But one thing can make you happy: I was wondering what the dumbest thing I'd read or hear today was going to be, and here at just 2am, you already provided it for me. Mystery solved.
No offense, but that just doesn't make the slightest bit of sense.
Why stifle creativity? Why hold back people who get into the race?
Tell me this: I bet in your district there are a few boys who can run a lot faster than anyone else. Probably partially because they're just fast, and partially because they play sports and generally work on getting faster and faster.
So if they were going to have foot races....are you going to make everyone wear clogging shoes to be sure someone doesn't have a nicer pair of shoes than the others? If you did, you DO realize that the fastest kids will still win, right?
It's the same for Pinewood Derby. It'd be the same if you held a video game contest where the boys all played Call of Duty. The kids that played the game the most would win.
It'd be the same if you held a computer building contest...the kids with the Dads who worked in IT would have an advantage. And so on.
Relax your rules and let everyone have fun.