The load range is chosen based on the weight resting on each tire. Weigh your Mallard, front and rear axles separately and divide the axle weight by 2 to estimate how much weight rests on each tire. The rear axle probably carries more weight. Then consult with a tire dealer who will look up the Load Range needed to carry that much weight. If you can't weigh the rig, use its GVWR rating and divide by 4, then add a few hundred pounds. That should give you are fair estimate. If in doubt or near the boundary between two ranges, go for the higher range.
You need the weight figures to determine how much air to put in the tires too. Every tire has an inflation table which dictates how much air is needed to carry a given weight. You must have that recommended psi to be safe and to prevent premature tire failure. Any more than that psi will cause an unnecessarily harsh ride. The max psi shown on the side of the tire is NOT the recommended amount unless the tire is carrying its max rated load.
Welcome to the RV Forum. We are happy to see you here and hope that you will make this a regular stop when you are on lline. We have a good group of knowledgeable RVers here and you should be able to get answers to most any question you might have regarding RVs and RVing. I see that you alreaddy have a good answer to your question regarding tire load range for your 22 Ft Mallard. I hope that this satisfies your question. If you need more help, come on back and ask away ;D
Welcome to the RV Forum and Framily.? I see Gary has already provided the information you requested and I don't think I could add any more useful information.? Please enjoy the forum and feel free to participate in any of the discussions or start a new discussion.? For more information on tires a d tire saftey please click HERE