I would say a little plastic rubbing on turns is "SAFE" operating.
http://www.e-laws.gov.on.ca/html/reg...s_900625_e.htm
Ontario:
Highway Traffic Act
Code de la route
R.R.O. 1990, REGULATION 625
TIRE STANDARDS AND SPECIFICATIONS
5. A tire fitted on a vehicle shall not,
(a) be of a smaller size than the vehicle manufacturer’s specified minimum size; or
(b) contact any vehicle component so as to affect the safe operation of the vehicle. R.R.O. 1990, Reg. 625, s. 5.