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sgothard -> RE: 22" wheels (4/7/2007 12:24:30 AM)
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From the National Highway Trafic Safety Administration
However, NHTSA has been presented with data demonstrating that a very small number of replacement tires may cause a vehicle’s TPMS to exhibit functional problems for which there is currently no clear solution. The identified problems are primarily related to the tires’ construction (e.g., run-flat tires) and material content (e.g., high carbon content in low aspect-ratio tires, thicker sidewall, or steel body ply sidewall).
In many instances, TPMSs may function properly even when equipped with replacement tires with the above-mentioned characteristics, but to date, it has not been possible to develop an appropriate performance measure that would reliably identify those anomalous tires that would prevent proper TPMS functioning. However, available data show that, in 2002, light vehicle tires having either steel body ply cords (steel casing tires) or run-flat capability accounted for less than 0.5 percent of tires distributed in the United States. [4]
Based upon the above new information, we now believe that there is not a sufficient basis to require vehicle manufacturers to assure compliance with all replacement tires. While the number of tires expected to be incompatible with a given TPMS is expected to be small, such a requirement would nonetheless raise significant practicability concerns. For example, vehicle manufacturers will not be able to anticipate future tire construction changes; therefore, a replacement tire requirement similar to the one contained in the June 2002 final rule could force vehicle manufacturers to halt vehicle sales over a problem they could not correct. We continue to believe, however, that the TPMS should continue to function properly beyond the point at which the vehicle’s original tires are replaced, a clearly foreseeable event. At a minimum, consumers need to know if the TPMS is not functioning with the replacement tires. Otherwise, an unilluminated low tire pressure telltale would give consumers a false sense of security in those cases.
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