DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Parts 571 and 585
[Docket No. NHTSA 2005-20586]
RIN 2127-AJ23
Federal Motor Vehicle Safety Standards; Tire Pressure Monitoring Systems;
Controls and Displays
Final rule here
From the rule in the response to public comments section:
Quote:
15. Over-Inflation Detection
Table of Contents
ETV commented that, although requiring the TPMS to monitor high pressure is as important as monitoring low pressure, the NPRM did not consider or address this issue. ETV stated that manufacturers specify a safe maximum tire pressure, and that the final rule should address this aspect of vehicle safety. ETV�s comments recommended an intermittently flashing yellow telltale warning when the vehicle�s tires are within five percent of their maximum inflation pressure and an intermittently flashing red telltale when the vehicle�s tires have exceeded the maximum inflation pressure.
We have decided not to adopt a requirement for over-inflation detection for the following reasons. First, the TREAD required a rulemaking to detect a significantly under-inflated tire, not over-inflated tires, so such a requirement is arguably outside the scope of this rulemaking. Furthermore, we are not aware of vehicle safety data reporting over-inflated tires as a significant safety hazard. In addition, available information does not suggest that over-inflation has the same safety implications as under-inflation, which causes heat buildup in a tire, potentially leading to permanent tire damage and sudden failure.
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Surely if inflation above placard pressure was dangerous the NHTSA would have addressed it no?
I also like to point to the following study comissionned by the Dutch Ministry of
Housing, Spatial Planning and the Environment :
The influence of tyre pressure on the comfort
Quote:
The best possible option is still the recommended tyre pressure, specified by
vehicle and tyre manufacturers. It provides the best combination of aspects like
handling performance, comfort, wear, noise, etc. To come to the requested
vehicle-tyre performance level, a lot of knowledge, objective and subjective testing
is required.
However, considering the goals of the “Uitvoeringsnota Klimaatbeleid” [their policy to control climate changes], a
contribution is expected from increasing the tyre pressure of passenger vehicles to
reduce fuel consumption and therefore exhaust gasses. According to this research,
this is not possible without affecting other aspects of the tyre. Nevertheless an
increase of 0.2 bar (advised tyre pressure plus 10% an all tyres) is not significantly
changing the handling behaviour of the vehicles and is therefore seen as
acceptable. Considering the fact that low tyre pressures are worse because they can
negatively affect the behaviour of vehicles and lead to high tyre wear, the increase
of 0.2 bar can help to avoid these pressures.
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If a government is suggesting people go with higher inflation pressures, they must be damn sure it does not pose a risk.