National Traffic and Motor Vehicle Safety Act of 1966 (Safety Act), S571.120 Tire/Rim Selection, S5.1.2, requires the sum of the maximum load ratings of the tires fitted to the axle shall be not less than the gross axle weight rating (GAWR) of the axle system specified on the vehicle's certification label required by 49 CFR part 567. 567.77 requires any alterer of the vehicle to continue conformity with these requirements and assumes legal liability for certification under the Safety Act. The Siberian RV (see pic) is a customized off-road expedition vehicle manufactured by ProVan Industries, West Columbia South Carolina. They utilize a Ford F550 Super Duty 4x4 as the chassis and customize the RV to travel into off-grid extreme environments and road conditions. Provan alters the standard Ford F550 dual rear wheel to a single rear wheel The altered Certification Label affixed to the vehicle (see pic) establishes the rear axle GAWR at 14,706 pounds. The Tire/Wheel (Rim) assembly chosen by Provan as their alteration is listed as a TOYO M608Z 285/70R 19.5" on a Hutchinson Beadlock Wheel. ProVan neglected to list the capacity of this tire on the Certification Label, instead filling "X" in this spot (VIOLATION). TOYO Inflation Chart determines the MAX load capacity of this tire to be 6395# at 125 MAX Inflation (see chart). The Hutchinson Wheel has a stamped MAX inflation capacity of 120psi which lowers the load capacity of the tires to 6185# per tire. Either way the sum of the maximum capacity of the tires is either 12,790# or 12,270# safely. The tires are far short of the 14,706# required by the Safety Act. At 22,500 miles and roughly 50% tread wear the rear tire sidewalls developed a split in the bead seam near the rim (see pics). This unsafe tire condition was noticed and immediately pulled out of service. Toyo states this is an overload condition. ProVan refuses to take responsibility for their defective design in violation of the Safety Act. Please Help
NHTSA ODI 11421714