At the speeds you're (probably) riding at, balance is not going to be a huge concern. On the tire sidewall there should be a coloured spot - this should align with the air valve when the tire is mounted on the rim. Do this and the balance will be pretty close.
(however if you are using rimlocks then balance will definitely be an issue, unless you use two rimlocks 180 degrees apart)
If you do want to balance, car weights are fine if you an find some way of making them stay in place. You could use the adhesive backed strip that is used to balance alloy (car) wheels. Another method is to use strip solder, wrapped around the spoke and tape over it.
(Edit) I didn't understand you meant that "could you use a car tire balancing machine" (in Mexico) - I've never seen an automotive wheel balancer that will take a bike wheel, but that doesn't mean they don't exist)