A few posts back, I discussed the importance of using forged aluminum wheels as opposed to the less expensive, weaker cast aluminum wheels offered in the aftermarket and as standard equipment on some RV products. Almost as if to illustrate the point, a gentleman brought in a huge triple-axle fifth wheel trailer that had experienced a critical wheel failure. We’ve all heard of tire blowouts, but in this instance it was a wheel blowout; the explosion was so powerful, it blew the outside lip right off the wheel. He told me that the tire came off the rim completely and travelled down the highway.
Closer examination revealed that the wheels were rated to 3,500 lbs. and 110 psi, and the other Goodyear tires were inflated accordingly. Unfortunately, the manufacturer of the trailer had tried to save money using cast-aluminum wheels, which were made in China. From my experience, Chinese manufacturer ratings don’t necessarily mean much when the wheel is loaded to its maximum. Besides that, castings just don’t have the same strength as forgings-the forging process creates a much denser molecular structure.
Having experienced such a violent wheel failure, you would think that the owner would want to make sure it didn’t happen again. But instead, he wanted to replace the cast wheel with another one, or failing that, steel rims as a replacement. My concern was that the same thing would happen with another cast aluminum wheel, and we have seen inexpensive steel wheels crack before. That’s why we recommend a forged wheel like an Alcoa or Accuride-they’re a lot more expensive, but in a product like this, you get what you pay for.
The tires were also exhibiting unusual wear patterns. After checking it out, we found that this trailer’s alignment was the worst of both worlds-it was both toed in and toed out too much. The front axle was toed in ¼ inch, the middle axle was towed out .18-inch, and the rear axle was toed out .26. In addition, the middle axle’s thrust angle was off by .23 of a degree, and all three axles had negative camber (where the top of the tire is leaning inward), which, when combined with the toe-out condition, will wear out a tire very quickly. When we were finished with the trailer, the toe in was set at .07-.09 inch (some toe-in is necessary in the static condition so that it is at or close to zero in the dynamic or moving condition), and the camber was set at between zero and .02 of a degree. The trailer will now have a lot less resistance going down the road.
An alignment job like this takes several hours to perform, and the customer was uncertain about spending that kind of money. However, it’s important to take into consideration that the Goodyear tires on this particular trailer cost $350-$400 a piece with mounting and balancing, and there’s six of them. And don’t forget that misalignment causes drag, and drag reduces fuel economy.
The customer also indicated that he had one disc brake caliper on the trailer that was not working. He wanted to have it rebuilt, but there was no kit available, so I offered to order a new caliper for him, which might take a few days. He declined. So in the end, he drove out of here with correct alignment, but with a spare cast aluminum wheel and one brake caliper that still was non-functional.
Believe me when I tell you that I understand that everyone is tightening their belts right now-but your wheels, tires and brakes are not the right places to try and save money.