geared motor

[Espeefan]

It's all dependent on your model's wheel diameter is, the voltage you want to run, and what kind of scale speed you are after! It's really hard to just suggest the right motor, without knowing all these other factors. Usually something around 20-35 RPM at max voltage gives you a decent scale speed, with a 6" tall tire. Or about 1.6 actual miles per hour, on the high end. 16 scale miles per hour, on a 1/10 scale model. Or 22 scale miles per hour on a 1/14 scale model, which is fast for a loader. It's all in the math.

[rc4ever]

Thanks espeefan for the wonderful answer!! I've recently bought the geared motor with 5rpm output speed on ebay (I didn't pay attention for the rpm output speed, my fault) It's very powerful but way too slow! :-( I'm planning to buy another one but unsure about the proper rpm output speed, that's why I asked for a suggestion? If u take a look the pics of my dump truck "construction equipment- rc adt dump truck" and let me know what rpm should I go for?
Thanks again!
Leon