I dont' know if I should hire attorney or not.

Careless Driving is defined as driving in a careless and imprudent manner without due regard to the roadway conditions (curves, traffic, etc.).  Sounds like the damage was not much.  Careless is a 4 point offense.  If the 4 points would give you 12 or more points in the one year period prior to this incident or 18 points in the two years, then you should definitely get a lawyer.  If not, then you might want to go to the first court date yourself and see if they will offer a plea bargain (2 points defective vehicle or 3 point too fast for conditions?) that you are willing to accept.