I should have checked before I wrote this! The tire pressure check is required by the (California) Air Resources Board in order to reduce excessive emissions caused by running underinflated tires. Shops have to have a reference list of "recommended" tire pressures available. Mike Moore On Apr 7, 2011, at 11:33 AM, Michael Moore wrote: > > On Apr 7, 2011, at 11:00 AM, Keith Boonstra wrote: > >> Too often we find that "recommended" pressures are not necessarily >> optimal, but they yield a value that has greater importance to the >> specifier of the recommendation than it does to you as the final user. >> E.g.- American Classic wants your whitewalls to last, or Chrysler wants >> you to feel like you're getting a softer ride. >> > Keith, I guess I have to wonder about where the interests of the tire industry lobbyists, > insurance companies, car manufacturers etc. are in this. > Who sponsored the law in California to insist that ALL cars have their tire pressure checked whenever a car comes in? > I'm not a conspiracy theorists in general, but laws like this seem to be in someone's interest. > >> For more decades than I'm ready to admit I've had a practice in setting >> my tire pressures that has worked extremely well. I take very precise >> measurements of the tread depth on a brand new set of tires when I first >> get a different car, then I inflate them to a pressure I suspect will >> provide an even wear across the footprint of the tire. After I put on >> five or ten thousand miles, I go back and take exacting new readings of >> the tread depth to see how much they are wearing - the fronts may very >> well be different from the rears. If the outer edges are down, I'll add >> a pound or three. And likewise, if the centers are wearing a little >> more I'll lower the pressure some. Once I get the pressures set for a >> completely even wear, I'm good for as long as I own that car using >> similar tires. >> > My case is probably pretty different. I replace my tires based on age, not wear. > That's true of many of my friends with collector cars. My E Type has very expensive Dunlop tires which I'll have to replace. > The tires have less than 20,000 miles on them-but are 8 years old. So whether or not my American Classic tires make it to 45,000 miles is a moot to me. > >> >> In most of my radial tired cars with all-season tires I do find that the >> 35-36 pound range gives me that even wear. >> > I can not disagree. >> But, that being said, I live >> in Michigan and going to the Bridgestone Blizzak winter tires for ice >> and snow traction presented an interesting case in point. I found out >> that these tires are constructed very differently. When I first started >> running them I pumped them up to my regular 35-36 pound range and took >> off down the road without another thought. About 15,000 miles later I >> found I had run the centers right out of them. The centers were wearing >> at least twice as fast as the outers. >> >> I found that I had to drop all the way down to 29-30 psi to get those >> Blizzaks to wear evenly. I've had nine sets of them over the years, and >> dropping to that low figure has given me completely even wear on all the >> cars I've used them on. >> >> > >> It's amazing how much difference a little change in inflation makes, but >> then on the racetrack they'll adjust by as little as 1/2 pound on a >> single corner of the car and win (or lose) a race on it. Bottom line is >> that every tire was designed to have a certain flat footprint. The >> size, design, and construction of the tire, and the weight you press >> down on that particular corner, will determine what the real optimal >> pressure for that tire is. You just have to measure and find it. >> >> > I bled my American Classics down to 28 lbs this morning > (from the 38 they were) and I like the car's ride and handling much better. If the worst tghat happens is that the whitewalls > crack, so be it. > > Mike Moore >> Keith Boonstra >> >> - >> >> On 4/7/2011 1:11 PM, Bob Jasinski wrote: >>> >>> Mike, >>> >>> I run 35 PSI in all my vehicles and have for years. I've never had a >>> problem, get good mileage and handling, and tire shops I've worked >>> with all >>> recommend it. All my vehicles have radial tires and include my 300G, >>> Dakota >>> pickup, PT Cruiser, 2006 300, Chrysler Town & Country van as well as >>> my '88 >>> BMW 325i >>> >>> Bob J >>> >>> From: Chrysler300@xxxxxxxxxxxxxxx >>> <mailto:Chrysler300%40yahoogroups.com> >>> [mailto:Chrysler300@xxxxxxxxxxxxxxx >>> <mailto:Chrysler300%40yahoogroups.com>] On >>> Behalf Of Michael Moore >>> Sent: Thursday, April 07, 2011 10:04 AM >>> To: Chrysler 300 Club International >>> Subject: [Chrysler300] TIRE PRESSURE >>> >>> >>> Here in California, a new law went into effect which requires garages to >>> check tire pressure whenever a car comes in for service. >>> >>> I believe in factory recommended tire pressure as a baseline. The standard >>> herein Ca seems to be 35 psi. >>> My 2007 Subaru, my 1997 Benz, as well as my 59 TR3 have all had the 35 >>> pound >>> treatment and they each ride like an oxcart and steer differently at that >>> tire pressure. The Benz ought to be 28 all around, the TR ought to be >>> 22 and >>> the Subaru something else ? but lower. >>> >>> They all are much nicer to drive with FSM correct tire pressure. >>> >>> My 300H picked up 38 psi last week while visiting the garage. >>> The FSM specifies 24 for the 300H. >>> In 1968 when I bought my first set of Michelin X's for the 300H, the >>> Michelin dealer said they would look low at 24 because they were >>> radial, but >>> the only reason to pump them up was if people kept telling me they >>> were low! >>> >>> This morning I noticed American Classic, the mfgr. says to keep them at 35 >>> psi or the whitewalls will crack. >>> >>> Any experience with that? (I don't like 35!) >>> >>> Mike Moore >>> Morgan Hill, Ca >>> >>> [Non-text portions of this message have been removed] >>> >>> >> >> [Non-text portions of this message have been removed] >> >> > > > > [Non-text portions of this message have been removed] > > > > ------------------------------------ > > To send a message to this group, send an email to: > Chrysler300@xxxxxxxxxxxxxxx > > To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or > go to http://autos.groups.yahoo.com/group/Chrysler300/join and select the "Leave Group" button > > For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm > > For archives go to http://www.forwardlook.net/300-archive/search.htm#querylangYahoo! 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