Date: Thu, 05 Jun 2003 10:37:41 -0400 From: CS <> Subject: Re: Tire Suggestions for 9KT
Okay, I did a quick check on the "maximum inflation pressure " means cold pressure notion, and I am correct, max = cold. I don't have the presumed CFR cite that sets forth the standard, but I do have the next best thing: US DOT (NHTSA) has posted a notice of proposed rule making to change 49 CFR Parts 567, 571, 574 and 575. Therein, the agency writes: "The recommended inflation pressure is often confused with the maximum inflation pressure which is labeled on the tire by the tire manufacturer to provide the maximum cold inflation pressure to which a tire may be inflated based upon the maximum load rating for that tire. Maintaining tires at their proper inflation pressure, instead of allowing them to become underinflated, reduces heat build up, minimizes tire wear, contributes to good vehicle handling and improves fuel economy through decreasing the rolling resistance of the tires." see: http://www.nospam/cars/rules/rulings/TREAD/NPRM/Index.html On Wed, 04 Jun 2003 18:20:59 GMT, "Fred W." f92sdvgvjl0gqdk6k1it0jcism8h994u15nopsamcom... >> Thanks for the responses. > ><<snip>>> > >> I do run my summer tires with above normal air pressure: 42 lbs. all >> the way around (cold). But have done so for 15 years, on Michelin >> XGTV, XGTZ, the aforementioned Pirellis, and the Dunlops. I read with >> interest Uncle Bob's recent post about being careful to not put much >> air in the tires, as the pressure increases as driven. With all due >> deference to Bob, I think max pressure is cold pressure, > >Definitely not. Bob's quite right, air expands as it heats, so the pressure >increases. 42 psi is pretty high to be running around town. I can see >running that high for an autoX but I'd lower the pressure down some for >general highway droning. It may be that you somehow overstressed the tire >carcass by running with such high pressure. > >> but in any >> event those Dunlops had max rating of 50 lbs. > >That *is* high. Most Z rated tires I see are rated at 40 - 45 lbs max. But >I would not run them that high. >> >> My point in all this is that it is neither my car, nor my driving that >> is causing the sidewalls to go. It appears more likely that I've >> gotten tires with manufacturing and/or design defects. >> >> Moreover, cords do slip within tires -- if I'm not mistaken, that is >> precisely what was happening with the Bridgestones involved in the SUV >> rollovers. > >They were Firestones (on the Ford Exploders) and the problem was caused by >sidewall blowouts due to underinflation. The manufacturer reduced the >inflation spec to try and reduce the number of roll-overs happening in >evasive manuvering. The problem is that all the soccer moms forgot to check >the air pressure now and then and ran them seriously under inflated. This >causes huge increase in tire temperature and eventual self destruction. > >> >> I think I might try the Kumho's >> >> > >Go for it. They are pretty good for the $$ > >-Fred >
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