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CWtheMan · 10-17-2018, 05:53 PM

This subject will normally be hotly debated when it comes-up in tire forum threads. In this presentation I’m going to provide information from numerous references. It’s the only way a reasonable explanation of misapplications can be described. Try to remember, when reading this, that I’m presenting this information from numerous regulating regulations and tire industry standards.

The reference to a tire being misapplied is most commonly found in individual tire manufacturer tire warranty information documents. In that context they just use the word without any explanations. That opens the door to all sorts of speculations. For this presentation the word misapplication means, to use something for the wrong purpose or in the wrong way.

For there to be an official wrong way there has to be a precedent somewhere that describes the wrong way. Sure enough, there is. It’s in an active federal regulation for tire inspections. Here is the verbiage; “A mismatch in size and construction between tires on the same axle, or a major deviation from the size recommended by the vehicle or tire manufacturer, is a cause for rejection.” The prefix in this tire size example, LT235/85R16 is officially part of the tire’s size. Therefore, LT describes a tire designed primarily for Light Truck applications. In this size, ST235/85R16, the ST describes a tire designed for Special Trailer service. One used in place of the other is a major deviation.

There are several ways to work around the misapplication. One is to use tires clearly marked with , “ for trailer service only”, on their sidewalls, to replace ST tires. The most common tire in that category is the Goodyear G614 RST. Another option is to ask the vehicle manufacturer to approve a replacement tire, of your choice, for replacing the OE tires they installed on your trailer. NHTSA approves the use of an axillary tire placard, adjacent to the original placard, when ‘plus sized” tires are approved and installed as replacements. It needs to show the replacement tire size, maximum load capacity and recommended cold inflation pressures. I’d also want a signed endorsement from the vehicle manufacturer supporting their approved use of such replacements.

10-17-2018, 05:53 PM	#183
CWtheMan Senior Member Join Date: Feb 2010 Location: Taylors, SC Posts: 3,031	Misapplications of replacement tires This subject will normally be hotly debated when it comes-up in tire forum threads. In this presentation I’m going to provide information from numerous references. It’s the only way a reasonable explanation of misapplications can be described. Try to remember, when reading this, that I’m presenting this information from numerous regulating regulations and tire industry standards. The reference to a tire being misapplied is most commonly found in individual tire manufacturer tire warranty information documents. In that context they just use the word without any explanations. That opens the door to all sorts of speculations. For this presentation the word misapplication means, to use something for the wrong purpose or in the wrong way. For there to be an official wrong way there has to be a precedent somewhere that describes the wrong way. Sure enough, there is. It’s in an active federal regulation for tire inspections. Here is the verbiage; “A mismatch in size and construction between tires on the same axle, or a major deviation from the size recommended by the vehicle or tire manufacturer, is a cause for rejection.” The prefix in this tire size example, LT235/85R16 is officially part of the tire’s size. Therefore, LT describes a tire designed primarily for Light Truck applications. In this size, ST235/85R16, the ST describes a tire designed for Special Trailer service. One used in place of the other is a major deviation. There are several ways to work around the misapplication. One is to use tires clearly marked with , “ for trailer service only”, on their sidewalls, to replace ST tires. The most common tire in that category is the Goodyear G614 RST. Another option is to ask the vehicle manufacturer to approve a replacement tire, of your choice, for replacing the OE tires they installed on your trailer. NHTSA approves the use of an axillary tire placard, adjacent to the original placard, when ‘plus sized” tires are approved and installed as replacements. It needs to show the replacement tire size, maximum load capacity and recommended cold inflation pressures. I’d also want a signed endorsement from the vehicle manufacturer supporting their approved use of such replacements.