Posted by Vaughn [172.69.140.161] on Wednesday, September 20, 2023 at 09:38:51 :
In Reply to: Re: Speedo Drive Gears 5x16 works perfect for mich 11.00x16 posted by Chris Case [172.69.33.200] on Wednesday, September 20, 2023 at 08:14:53 :
Chris, you're correct on the 4x14 for a 5.83:1 ratio with 900x16 tires, but he changed to the 4.89:1 ratio with 900x16 tires that's why he is looking for the 5 tooth gear. When you measure your tires, you have to measure from the ground to top of the tire since that will be the true height under the weight of the vehicle. You can't use an unloaded diameter that's why I used 37 inches for 1100 and 35 for 900 and assuming most guys run 40-45 pounds of air pressure for either tire. My 1100 tires mounted on my truck are 37-3/4 tall at 60 pounds of air, most guys don't run that amount, 40-45 probably. Using my tire height of 37-3/4 inches, the pinion gear I would need is a 13.0 tooth for an accurate speedometer reading where the 40-45 pounds, the reading of the speedometer will be off. Since my pinion is a 14 tooth in the TC, my speedometer reads a few miles slower than it should.
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