Posted by Matt Wilson [108.162.221.239] on Sunday, December 23, 2018 at 18:17:41 :
In Reply to: Re: 4.89 gearing posted by Andrew in MI [172.68.58.68] on Sunday, December 23, 2018 at 15:40:42 :
I'm pretty sure the answer is no. Dividing the ratio of 5.83/4.89 gives you the percent increase in speed of the 4.89's vs. 5.83's, which is 19.2%. If you divide the rolling radius of an 11.00 x 16 tire by the rolling radius of a 9.00 x 16 tire, I don't believe you'll get nearly as much of an increase. I have a 9.00 x 16 tire as my spare, and its radius measures about 17-3/8". I have Michelin XZL's for the four tires that run on the ground, and their rolling radius is about 18". The radius of the spare is not the true rolling radius, since it's not on the ground with the weight of the truck on it, but if we were to say its rolling radius was 17", then dividing 18" by 17" gets you only about a 5.9% speed increase. The rolling radius of any given tire size varies depending on manufacturer, but I doubt that comparing 11.00 x 16's to 9.00 x 16's for most manufacturers, oe even comparing across manifacturers, would get you a 19% increase in rolling radius (i.e. road speed). So I would not purchase 11.00 x 16's, thinking that you'll get the same effect as a gearing change from 5.83 to 4.89.
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