Ontario, CA Parking Rules: Oversized Vehicle Parking (2026)

The unincorporated County regulates oversized and heavy vehicles through several overlapping rules rather than one ordinance defined by length or height. County Code Section 52.0125 (Weight Limitations) and Section 52.0128 (Restriction or Prohibition of Parking of Commercial Vehicles) authorize weight-based restrictions and parking prohibitions for large commercial vehicles on County streets; Section 52.0131 addresses prohibition of certain vehicles on highways. These sections are cross-referenced in Development Code Section 83.11.100, which uses a 10,000-pound manufacturer's gross vehicle weight rating as the threshold for 'commercial vehicles' and sets detailed residential-parking rules (acreage minimums and 5-foot, 15-foot and 70-foot setbacks) for truck tractors and trailers. For non-commercial oversized vehicles such as large RVs and trailers, the principal street limit is the 72-hour continuous-parking rule of County Code Section 52.0119, together with California Vehicle Code Section 22500's location prohibitions. The Vehicle Code also restricts how oversized loads and vehicles may travel and stop on highways. In the Mountain Region, additional seasonal and snow-removal parking controls apply on posted roads. Because there is no general posted oversized-vehicle permit system on most unincorporated streets, owners of large RVs, trailers and trucks should focus on the 72-hour rule, the commercial-vehicle weight thresholds, and posted local signage.