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GUARANTEED TIRE FAILURE! By John Anderson Sometimes it takes a tragedy, like the recent fatal motorhome accidents, to wake us up to something that we really already knew we should be concerned about, but just never gave it a priority. After all, bad things only happen to other people, right? After 8 years and having weighed more that 10,000 RVs, I can tell you with confidence that thousands of RVers are traveling down the road on overloaded tires that could fail at any time, with potentially catastrophic results. Does this alarm you? I HOPE SO! And, if your safety doesn't concern you, how about the fact that operating on our highways over a tire rating is in violation of government regulations? Does that concern you? Does the fact that members of our RV family are dying on the highway hit close to home? A'Weigh We Go is a POSITIVE SAFETY EDUCATION Program, and it is not our style nor intention to endorse or condemn any product or manufacturer. We accomplish our goals through education! I don't normally write "alarming" articles, but sometimes we feel extremely frustrated when we don't seem to be getting our message across, and when we are in possession of information that not only can save lives, but can predict the loss of life! Our goal is to ensure that every RV owner understands tire loading limitations and VERIFIES that his or her coach is operated safely. I recognize that not everyone has an opportunity to attend an A'Weigh We Go Safety Seminar, so let's review the basics. Tires, like most everything else we make, are designed to operate within a specific load; we call this tire load rating. On the sidewall of your tires you will find a rating for a single application (the front or tag of your truck/motorhome or your trailer axle) and a dual tire rating (the drive wheels). This rating is accompanied by an inflation pressure that, if used, will give you the stated rating. This DOES NOT MEAN that this inflation pressure is correct for your RV! Inflation pressure must be set based on the load being carried by the tire, if you wish to achieve optimum life and performance from your tires. Every tire manufacturer publishes LOAD/ INFLATION tables for their products, which provides us this critical information. I suspect that most RVers already understand this basic information, but where I fear the message is being lost, is in the manner in which we use these tables. We need to recognize that RVs are not built symmetrically! Of the more than 10,000 RVs we have weighed, we have never weighed one that was loaded equally on both sides! Think of it; you would not expect to! We have slide out rooms, generators, refrigerators, holding tanks, fuel & water tanks; the list goes on & on. The only way to properly weigh an RV to ENSURE that you are within your tire ratings is to WEIGH IT BY INDIVIDUAL WHEEL POSITION! Once you have done this, NOW you can go to the load/ inflation table to determine the correct inflation pressure for your tires. If the load is greater than the maximum rating shown on the sidewall, YOU MUST CORRECT THE SITUATION, either by reducing the load on the tire by unloading or redistributing the equipment in the coach, or upgrading your tires to ones with a higher load capacity. Tires come in many different load ranges, so it may be possible to change to a higher load rating tire within the same size, but BE SURE YOU DO NOT EXCEED THE LOAD RATING OF THE WHEEL! If you change tire sizes, be sure you consult with an industry expert, to ensure that proper fitment and vehicle compatibility is maintained. Be certain that you have the correct load/inflation table for the MANUFACTURER of your tire! Different tire manufacturers use different specifications! For example, you CANNOT use a Michelin table for most sizes larger than 16 inch for other tire manufacturers. If the tire size matches, AND the data on the far right of the table for your load range matches the information on the sidewall of your tire, then you have the correct table. Find the load you measured on the applicable line, dual or single, and move up to the corresponding MINIMUM inflation pressure for that load. Since your RV weight varies considerably with fuel, water , groceries, etc., it is important that you weigh your unit in it's heaviest configuration, or how you normally travel. Since inflation tables give us the MINIMUM pressure to carry the load, we suggest that you move to the right one block, or 5 psi, to give you a safety margin. We normally recommend that all trailers tires be set to sidewall pressure due to the higher loads that result from trailer sway. The Tire & Rim Association manual indicates that we can inflate our tires 10 psi over the pressure indicated on the sidewall for Light Truck (LT) tires, and 20 psi for truck & bus tires, however, this DOES NOT increase the rating of the tire, but simply helps it to run cooler. If you find that your load exceeds the chart rating, address the cause, YOUR COACH WEIGHT! Don't try to compensate by straining the capacity of your tires. You can expect to find a different load on each side of the axle. It is important that ALL TIRES ON THE SAME AXLE BE SET TO THE SAME PRESSURE, BASED ON THE HEAVIEST SIDE! If this results in an extremely overinflated tire on the light side, you should correct the situation by balancing your coach. An overinflated tire has reduced "tire patch", or contact with the road, and may result in unsatisfactory braking, particularly on a wet road. If you are unable to configure your coach so that it does not exceed a tire rating, contact your dealer or manufacturer immediately and ask for assistance. They do not want your safety to be at risk, but keep in mind, YOUR safety is YOUR responsibility! This weighing procedure and tire inflation pressure determination is important for all RVs, but CRITICALLY IMPORTANT FOR MOTORHOMES ON AIR SUSPENSION CHASSIS'. Our data indicates that 11 percent of all of the motorhomes we weigh exceed a tire rating without exceeding an axle rating, which means you would not detect the tire overload on a truck scale when weighed by axle only. However, almost 50 percent of some model air suspension motorhomes exceed a tire rating without exceeding an axle rating, and it is not uncommon for us to find tires that exceed their rating by more than a thousand pounds! This will pretty much guarantee you a tire failure! If you have an air suspension motorhome and have not weighed it by individual wheel position, I urge you to do so immediately. The risk is simply not worth another trip without verifying your safety. Please do not compromise your safety by accepting anything less than absolute assurance that you are not operating over a tire limitation. If you have been given "advice" that you should select your tire pressure based on ride quality, or how hot they feel to your touch, or how the tread wears, or anything other than measuring the load on your tires, you are not being given advice that is in the best interest of your safety! One other aspect of tire safety. TIRES DO NOT LAST FOREVER! We never worried about the age of our passenger car tires, because after a few years the tread was worn out, and we replaced them. But, in the RV world, it is common to find RVs that are perhaps 10 years old with less than 20,000 miles on them, so the tire tread looks good, yet the owner experiences frequent tire failure, and of course, blames the name of the manufacturer engraved on the sidewall for building defective tires. We cannot tell you exactly how long a tire will last because there are so many variables that affect aging of the casing, but we know from statistics that the average service life expectancy of a tire in RV service is 5 to 7 years. In fact, it is important to note that tires age more quickly when not used! Tires are designed to roll, heat up, and release anti-weathering chemicals that help to keep the tire supple and resist aging. In the RV world, we frequently subject tires to the absolute worse case scenario; We sit for a season in the sun and ozone, then pull onto the interstate and dash down the highway at speeds in excess of 65 miles per hour, then park it for a few months, etc., creating an extreme duty cycle. Every RV owner should know the age of the tires on his coach and be alert for signs of aging. The Department of Transportation (DOT) requires that every tire be marked on the sidewall with its "birthday", or when it was in the mold. Find a string of numbers and letters that starts with "DOT" on the sidewall. It's only on one side of the tire, so you may have to crawl underneath to see it. At the end of the string you will find three numbers; the first two indicate the calendar week of the year, starting with "01" in January. The third number is the year, so a "089" might indicate the tire was born on the 8th week of 1999. Unfortunately, not all manufacturers supply us with the decade, so this tire might be a 1999 or a 1989. You need to have some knowledge of when the tires were installed. Michelin provides a decade indicator; if you see a small arrowhead just after the last digit 9, it is a 1999 tire. Fortunately, our government has seen fit to resolve this confusion in the new millennium, so tires being built now have four digits; two for the week and two for the year. Be sure you know the age of your tires, and don't risk your safety for the few dollars (relative to an accident) a new set of tires will cost you. A'Weigh We Go is a SAFETY PROGRAM, and our educational seminars and weighing services are subsidized by our sponsors. It costs us about $70 to weigh an RV, but we only charge you $30, for which you get weighed by individual wheel position, a comprehensive weight analysis of your ratings versus your loads, and everyone gets a load/inflation table for their specific tires. You can find our weighing schedule on our web site at aweighwego.org, or call us at (423)257-7985, or e-mail us at info@aweighwego.org. We publish a comprehensive RV Weight & Tire Safety Handbook, which we sell for $15 plus $4 for packaging & shipping. The handbook contains all of the information we use in our Safety Seminars, and describes how to weigh your coach by individual wheel position. Simply send a check for $19 to: A'Weigh We Go, 211 Mae McKee Road, Chuckey, TN, 37641. Tire load/inflation tables are supplied without charge. Send a self addressed STAMPED business size envelope and include : Tire manufacturer, tire size AND load range, and the rating data from the sidewall, both maximum load and inflation pressure for single & dual. Requests without complete information cannot be handled. This article is not intended to be a sales pitch for A'Weigh We Go, but to save your life, so I urge you to find someplace to weigh your coach properly, AND, use the data to verify your safety.
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