a motor is a motor you need to look at the club or race rules if its allowed or not. Example Rule
-Trinity D3.5 not allowed for spec 17.5 races, MOD ONLY
-Trinity Short Stack 1 cell NOT Allowed for Class X or Race Y
-ROAR approved motor only Resistance XXX ohms


for the most part a 17.5 used in off road is the same 17.5 used for onroad. As long as you haven't overheated or abused the rotor/motor it should be more then fine.