I used to work at an American Tire Depot, and ive probably mounted more tires than i will drive on in my lifetime. But i did have to hand mount a few tires every once in a while, its not extremely hard, and if done correctly wont damage the wheel. Balancing is very hard without a machine. Usually anything more than 1 ounce out you will feel over 55mph, the average tire is 1-1.5 ounces out when mounted (assuming the wheel is straight, not bent, and the tire is new/isnt separated/worn uneven) So it SHOULDN'T take much to balance unless your getting into the big off road tires.
Then again I mounted a set of 37's on my truck and i didnt want wheel weights, so i mounted all 4, threw them on the balancer, and found out where the weights needed to go, pulled the tire off the machine, broke it down, and rotated the tire on the wheel, then beaded it back up and balanced again. I spent an entire day before I got all 4 wheels less than 1 ounce out with monstrous 37's, but i did it
