Issue link: http://read.dmtmag.com/i/34501
AIR PRESSURE REQUIREMENT The amount of air pressure required in each tire depends on the weight of the fully loaded vehicle. So the RV owners cannot determine the tire’s correct air pressure unless they know their vehicle’s actual weights. The maximum load capacity allowed for the size tire and load rating and the minimum cold air inflation needed to carry that maximum load are located on the tire’s sidewall. The lower the air pressure, the lower the load that the tire can carry. A complete load and inflation table is available at www.michelinrvtires.com; MICHELIN ® RV Tires: Guide For Proper Use and Maintenance and RV Tire Information – MWL43146; and the MICHELIN Data Book – MWL40731. ® Truck Tire WHEN TO CHECK RV TIRE AIR PRESSURE The RV owners need to know the correct air pressure per axle for their RV, and they need to know when and how often to check the MICHELIN ® RV tires. Here are a few recommendations for the RV owners: 1) Check at least once a month and before any major trips. 2) On long trips, check every morning before driving. 3) Check before and after storage. 4) On short trips of a day or less driving each way, check before you leave and before you return home. Always try to check tires when they’re “cold” and have not been driven for more than one mile. The stated load capacity for a given cold inflation pressure is based on ambient outside temperatures. The pressure in a “hot” tire may be as much as 10-15 psi higher than the “cold” tire pressure. If the RV owners must check the tires when they’re warm, be sure to allow for an increase in pressure, and make sure the pressure of the tires on both sides of the axle are within a couple of pounds of each other. Never let air out of a hot tire. To make checking the tire pressure easier and more accurate, Michelin recommends that the RV owners purchase a quality truck tire air gauge with a dual-angled head. This allows the RV owners to check the pressure of the inner and outer dual wheels. And the easier it is to check the pressure, the more that the RV owner will do it. Nothing should restrict the RV owner’s ability to check their tire pressure daily when driving their RV. Be sure to use pressure-sealing valve caps to prevent air from escaping the valve stem. If the valve stem extension hoses are used, make sure they’re good quality stainless steel braid reinforced and are securely anchored to the outer wheel. The joints should be soaped immediately after initial installation to check for air loss. If the RV has wheel covers, consider removing them since the extra time and effort they require could lead the RV owners to avoid checking the tire’s air pressure. DETERMINING THE RV’S CORRECT WEIGHT The GVWR (Gross Vehicle Weight Rating) and the GAWR (Gross Axle Weight Rating) stickers on the RV (normally located on the support pillar next to the driver’s seat) will show the chassis manufacturer’s and/or the RV manufacturer’s total vehicle weight ratings and per axle weight ratings. The GVWR is the maximum total weight rating — this includes passengers, fluids, and cargo. The GAWR is the maximum for a single axle. These ratings can vary based on a number of components, so RVs of the same make and model will vary because of different options and personal loads. That’s why the RV owners need to weigh their RV in a loaded condition to know its actual weight. Michelin recommends weighing each wheel position of the vehicle. Why? Because when you weigh the entire vehicle at once, it’s possible to be within the GVWR, but overloaded on an axle. And when you weigh one axle at a time, it’s possible for one wheel position to be overloaded even though the GAWR has not been exceeded (we’ve seen as much as a 1200-pound difference between left and right front tires). Weighing each wheel position will give you a clear indication of how the weight of the RV vehicle is distributed, so you can determine the correct tire inflation pressure. For instructions on how to weigh by wheel position, see next pages 74-76. Once you know total weight and weight on each wheel position, the tire load data chart will show you the correct inflation pressure for each wheel position. Section Five: MICHELIN RV Tires 73 ®