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## Re: [Tigers] Gas milage with different tires?

 To: "'Jim'" , "'Thomas Witt'" Re: [Tigers] Gas milage with different tires? " Ron Fraser" Mon, 5 Jul 2010 07:49:48 -0400
 ```Jim I have never seen a race team ever measure a tire like that, they always check the circumference, but I have never compared the measured circumference to the roll the car one tire revolution method. Yes the weight of the car compresses the diameter of the tire some but I doubt very much that the tire circumference can change more than a mm. It does pose an interesting experiment to compare these 2 methods. Tire wear can change the diameter by of the tire .5" or more; this changes the circumference the most. Ron -----Original Message----- From: tigers-bounces@autox.team.net [mailto:tigers-bounces@autox.team.net] On Behalf Of Jim Sent: Sunday, July 04, 2010 9:41 PM To: Thomas Witt Cc: Subject: Re: [Tigers] Gas milage with different tires? Measuring the 'off car' circumferance doesn't give you a very accurate 'tire revs. Per mile' as it's compressed on the bottom making the rolling diameter slightly smaller. When I sent the numbers to get a custom speedo gear for my Sprite/B210 5 sp. Conversion they asked that I mark the tire and ground with a chalk mark and then roll the car one tire revolution and make another mark on the ground and take a measurement between them to show 'rolling' circumferance... Jim B382000446 Sent from my iPhone On 2010-07-04, at 4:31 PM, "Thomas Witt" wrote: > Back in 2003 Ron Fraiser sent this to the list: > >>>> Good Question about the original tires. I don't know the real >>>> answer; I can only reverse engineer the size of the tire from the >>>> printed facts in the > manual and on hand. > > Original Tire = 5.90 x 13 - not much help here. > > 1-From the Tiger Manual - 23.92mph @ 1000 rpm Calculate tire size > using 2.88 gears Tire circumference = 72.75" - Diam. = 23.15" > > 2-Let's calculate again using the speedometer gear ratios. Speedo > cal# = 980 rev/mi, speedo cable gear = 15 teeth, > trans drive gear # B7C-17285-A = 6 teeth, 2.88 gears > This gives you 24.49mph @ 1000rpm > > Tire circumference = 74.48" - Diam = 23.71"<<< > > > A number of years ago (6 years to be more accurate) Jim Boynton sent > me the circumference of his original, barely used spare tire. It was > 74.875". > > So, for those that want to be "factory accurate" take your pick. > 72.25", 74.48", or 74.875 as each has its merits. In closing his > post Ron wrote, "I hope this helps and doesn't confuse people too > much." I would agree. > > Tom (Witt) > _______________________________________________ > Tigers@autox.team.net > Donate: http://www.team.net/donate.html > Archive: http://www.team.net/archive > Forums: http://www.team.net/forums > Unsubscribe/Manage: http://autox.team.net/mailman/options/tigers/jim@island.net _______________________________________________ Tigers@autox.team.net Donate: http://www.team.net/donate.html Archive: http://www.team.net/archive Forums: http://www.team.net/forums Unsubscribe/Manage: http://autox.team.net/mailman/options/tigers/rfraser@bluefrog.com No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.439 / Virus Database: 271.1.1/2977 - Release Date: 07/02/10 06:35:00 _______________________________________________ Tigers@autox.team.net Donate: http://www.team.net/donate.html Archive: http://www.team.net/archive Forums: http://www.team.net/forums ```
 Current Thread Re: [Tigers] Gas milage with different tires?, (continued) Re: [Tigers] Gas milage with different tires?, Ron Fraser Re: [Tigers] Gas milage with different tires?, michael king Re: [Tigers] Gas milage with different tires?, Dave Munroe Re: [Tigers] Gas milage with different tires?, e.coiner Re: [Tigers] Gas milage with different tires?, Tom Parker Re: [Tigers] Gas milage with different tires?, Thomas Witt Re: [Tigers] Gas milage with different tires?, Ron Fraser Re: [Tigers] Gas milage with different tires?, Jim Re: [Tigers] Gas milage with different tires?, drmayf Re: [Tigers] Gas milage with different tires?, drmayf Re: [Tigers] Gas milage with different tires?, Ron Fraser <= Re: [Tigers] Gas milage with different tires?, David T Johnson Re: [Tigers] Gas milage with different tires?, Thomas Witt Re: [Tigers] Gas milage with different tires?, CoolVT