Gary Barker wrote: > I have always put a small dap of Grease on the tire and then role the > car at least one turn of the wheel and then Measure the distance > between the grease spots. Gary Barker > > -------------------------------------------------- > From: "Michael Reed" <mrreed@xxxxxxxxx> > Sent: Thursday, January 01, 2009 4:29 AM > To: "Edward Mills Antique Tractors" <millserat@xxxxxxxxxxxxx>; "300 > Club Server" <Chrysler300@xxxxxxxxxxxxxxx> > Subject: Re: [Chrysler300] 300 L wheels & tires > >> The Web site mentioned (Car / SUV / Van / Light Truck Tire >> Calculator) can be very useful. I would like to caution readers, >> however, regarding the "Wheel Circumference" value returned. The >> number is accurate, based on the "Overall Wheel Diameter" provided, >> and is valid for a wheel/tire carrying no weight and inflated. The >> page calculates the circumference mathematically. >> >> However, mounted on a vehicle, unjacked, the tire has a "rolling >> circumference" -- and it is not the same value as can be calculated. >> The "flat" at the bottom, where the weight rests, creates a tire that >> is not round. I don't believe the actual circumference of a tire can >> be calculated accurately, as the "flat" on a tire with weight on it >> varies according to a number of factors. Back in my racing days, we >> had to physically measure the circumference using a tape measure to >> get an accurate circumference value. Due to the larger 'flat' on >> today's radial tires the difference between actual and calculated is >> even greater. >> >> As the "Wheel revolutions per mile" and "Wheel revolutions per second >> @ 65MPH" are derived from the calculated circumference, those values >> are inaccurate also. >> >> Mike Reed in flooded Lake Odessa, Michigan -- but the "F" is high and >> dry across the street.... >> >> ----- Original Message ----- From: Edward Mills Antique Tractors >> To: Larry Nirenberg >> Cc: rselby41@xxxxxxxxx ; 300 Club Server >> Sent: Wednesday, December 31, 2008 10:25 PM >> Subject: Re: [Chrysler300] 300 L wheels & tires >> >> >> Larry Nirenberg wrote: >> > >> > Before I guessed I would go to this web site and figure out an >> > equivalent to the OEM radius tire in a 15" size. If you do this the >> > tire will definitely fit- >> > >> > http://www.net-comber.com/tirecalc.html >> > <http://www.net-comber.com/tirecalc.html> >> > >> > ________________________________ >> > >> > From: Chrysler300@xxxxxxxxxxxxxxx >> > <mailto:Chrysler300%40yahoogroups.com> >> > [mailto:Chrysler300@xxxxxxxxxxxxxxx >> > <mailto:Chrysler300%40yahoogroups.com>] >> > On Behalf Of Roger Selby >> > Sent: Tuesday, December 30, 2008 9:29 PM >> > To: 300 Club Server >> > Subject: [Chrysler300] 300 L wheels & tires >> > >> > Hi 300 Friends, >> > I was driving my 300 L to the Sparks/Reno 300 Meet, last June, when a >> > gal >> > ran a RED light and took out my cars front end. A new clip, >> sub-frame & >> > 6 >> > months later, it is out of the body shop. Arbogast Body & Paint, >> Auburn, >> > Ca. did a great job & are super people. >> > >> > I am now looking to put on Magnum 500 wheels 15X7 inch & 235/75/15 >> > tires. >> > Will I have the clearance to run these larger, 15 inch tires? >> > >> > If anyone knows, please advise. >> > >> > Thank you, Roger Selby >> > Placerville, Ca. >> > 530-622-1020 >> > >> > [Non-text portions of this message have been removed] >> > >> > >> Diameter is only part of the problem - and don't for a minute believe >> that all the same size tires are the same size. check the referenced >> site for starters, but check vendor info on tire dimensions - >> especially >> tread width. On several 235/75R15 I looked at there was more than an >> inch difference in tread width - from 5.9 inches to 7.4 inches. If your >> OE tire was 9.00-14 - BFG tread width was only 4.8 inches. >> >> Don't know about your application and wheel offset will also be >> important - but on a non-letter 67 300, the 7.25 inch tread width on >> 15x6 with 0.5 inch inboard offset, they rub at both front and rear >> inboard edges at extremes of steering. Factory offset for the 67's was >> 0.25 inch inboard and I think the 15x7 are 0.25 inch inboard so they >> should be better than 15x6 with 0.5 inch inboard, but rub was at static >> condition - tires will deflect inboard a bit under hard cornering. >> >> >> >> >> [Non-text portions of this message have been removed] >> >> >> ------------------------------------ >> >> To send a message to this group, send an email to: >> Chrysler300@xxxxxxxxxxxxxxx >> >> For list server instructions, go to >> http://www.chrysler300club.com/yahoolist/inst.htm >> >> For archives go to http://www.forwardlook.net/300-archive/Yahoo! >> Groups Links >> >> >> >> >> > hey guys don't get too hung up on circumference. The only thing that circumference affects is speedometer error. And a paper tape measure of circumference is probably fine for a belted radial which will not grow significantly due to the belt stiffness. The older bias ply tires and especially race tires grew with inflation - typical cold pressures were in the low 20's and operating temperatures were typically 32-35 psi hot - and especially race tires on a hot day at 230F pyro temp would increase enough that you could feel it if you changed a rear on one side til it warmed up - but not to worry much about street belted tires on an antique. The 5 items you want to know are 1. diameter as it affects clearance; 2. static loaded radius as it affects car height and radials are lower than old bias tires at same diameter or circumference; 3. tread width as it and diameter affect clearance at steering extremes; 4. section width which is a function of tire and wheel - as this affects clearance to struts and other hardware; and 5. offset which is a function of wheel geometry only but will affect all lateral clearance issues. If you are really concerned with speedo error, consider most speedometers are off by a percent frequently more as speedometer pinions offer about a +/-2% calibration per tooth change - and a difference of 1 inch in circumference on a 90 inch circumference is only 1.1% or 60.6 mph vs 60 mph. best, Ed ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! 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