This seminar covered basic tire facts -- air pressure, size and comparisons, and was sponsored by Les Schwab and Toyo tires. Always make sure your tire rim diameter and the rim/wheel diameter are identical. Whenever possible, use tires of the same pressure on an axle. Use the higher pressure when two tires are unequal, as overinflation is far better than underinflation. If you change to tires of a greater load capacity, you will be able to use a somewhat lower tire pressure.
As coaches get larger and heavier, and since customers think it looks “better” to have a coach with a higher silhouette, tires are becoming larger and taller.
The 275/80 is the largest coach tire used for our Intrigue. The 275 number refers to the distance of the cross section width of the crown of the tire -- stopping short of the bulge. The 80 is a percentage of that number wheel rim to tire top.
To determine what tire pressure to use, weigh the coach after it is loaded. Loaded means all water and fuel as well as the “stuff” you will pack into the coach. This cannot be done at the factory, as many wish, because the coach will not have been loaded at this point. Only after the individual loaded weight is known for each wheel can a recommended air pressure be utilized using the load and inflation tables. Be sure not to exceed the tire rating. Tire manufacturers do not recommend overinflating to cure weight problems. Stick to what is printed on the sidewall.
Some common tire problems include sidewall cracking. Often caused by the sun, cover your tires whenever possible, expecially if the coach will remain in one position for a longer period of time. Do not use tire dressings (Eagle One products [which we believe they sell] were recommended, however.)
Air gauges. Recommended is a “180 reverse air gauge” which can get at both interior and exterior tires. Valve extensions are nor recommended, as the vibrations between the two dual tires can cause air leakage. Anything you add to the tire valve can lead to potential problems.
What causes delamination (“alligators”)? This could be caused by a bad tire from the start. Impact with a curb or like impediment bruises and weakens the tire. Heat must be present for delamination to occur, and this can come from underinflation, which weakens the sidewall and causes heat.
When you check your tire pressure, do it before you start up in the morning. If, for example, you were driving through a desert like area, it is very possible that it would take several hours for the tires to cool enough to get a reliable tire pressure reading.
Coach tires are probably due for rotation after about 25,000 miles. It is recommended that they be rotated as follows: move the front tires to the right hand rear. That set of duallies now becomes the front two tires. At the next rotation, rotate the front wheels to the left hand rear.