Motor size info please

[colonel]

I see motors listed as 540 or 550 size and wonder what that means? I assume it is the physical size of the motor but how do I know the difference? I have a bunch of motors here and wonder if they are 540 case or 550 case or something else? Is it the diameter or length?
I did not turn up anything on this in the search. I also read the excellent threads on motors and electronics to no avail. Anyone willing to help a newby with this? Or nudge me in the right direction to find this?

 

[Gardetto]

540/550

A 540 is the most common size 1/10 scale motor, and comes with about 95% of all RTR's . a 550 is common in a Nitro stater box or is sold by Traxxas in the Titan line and comes in the Slash,E-maxx. the 550 can is longer and steps down where the brushes are.

550




540

 

[colonel]

Thank you. That clears that up. I appreciate the assistance.