Tire inflation pressures for RV trailers. Itís a puzzlement many ponder often and are just as often off track when it comes decision time. It becomes complicated because there is as many bad answers given as there are good ones. I deal with regulations and tire industry standards. Thatís where this lengthy dialog will come from.
Confusing to the average consumer are the acronyms. GAWR = Grosse Axle Weight Rating. For all situations on our tow vehicles and RV trailers the GAWR is going to determine the selection of tires for fitment to them by the vehicle manufacturer to accommodate the vehicleís GAWR values displayed on each vehicleís certification label. Other factors are at play. GAWR values for automotive vehicles are not determined by the same factors used for RV trailer tire fitments. GAWR values for automotive vehicles most often differ in load capacity from drive to steer axles because of the required load they will carry. Plus, the regulations will require some reserve load capacity to be provided via inflation pressures. Most often your pick-up tires will be over inflated if the maximum pressures displayed on their sidewalls are used. On RV trailers the tires maximum amount displayed on their sidewall may be their only recommended inflation pressure.
Tire industry standards coincide with NHTSA standards when it comes to inflation of Original Equipment sized tires on your vehicles. The inflation pressures found on the tire placard, certification label and in the vehicle ownerís manual are the correct (cold) inflation pressures and are never - under normal circumstances - recommended to be lower than what is shown on the certification label. That is not an arbitrary statement because, NHTSA, via regulation, directs the vehicle manufacturer to set all recommended tire inflation pressures.
So, lets look at the correct inflation pressures for the G614 tires. If they were Original Equipment tires itís not arguable. Use what has been recommended on the tire placard. Those are steel cased tires. When they come apart for any reason they almost always do thousands of dollars of damage to the trailer.
Using G614 tires as replacements for other sized/designed tires; Tire industry standards are very clear on this procedure. Number one is to select tires that will have the ability to provide an equal or higher load capacity via inflation as the OE tires provided. To determine the inflation pressure needed for the target load capacity youíll need the load inflation chart for the G614 tires. Here is a hypothetical; Your OE tires were ST235/80R16E and their recommended inflation pressure was 80 psi providing 3420# of load capacity per tire. The correct inflation for the replacements would be about 96 psi. But, you got stronger tires for more protection so if it were me Iíd inflate them to 100 psi, write it on a sticker and place it beside the tire placard informing all others of the minimum inflation for the new tires. (NHTSA allows that action).
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