Mis-marked 70mm Medusa?

[Unsullied_Spy]

Originally Posted by _paralyzed_

gps it? eyeballing speed leaves much room for error. or make a speed trap.

+1. I can eyeball speeds of land vehicles pretty well but to be the most accurate you'll need to GPS it, radar it, or at very least use a speed trap (mark off 100 feet or so, see how long it takes to cross that distance then do the math). You'll need to be rather close on your estimates of tire ballooning, that could easily throw you off.