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Old 07-19-2019, 07:37 PM   #18
Synchro909
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Join Date: Jun 2014
Location: Melbourne, Australia
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Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Quote:
Originally Posted by Peyton View Post
Years ago, I had a Volvo 122S that could get to 100 with its stock tires (15 inch wheels). I changed to bigger rear tires and suffered loss of gas mileage and performance. Maybe it was the dynamics of that particular car that made the use of larger rear tires counterproductive.
The restorer of my '28 Tudor fitted a 3.54 diff. A later owner fitted a 26% Mitchell O/D. I am going back to reduce the overall ratio because it is too highly geared as it is in O/D. Economy is poor and it hates hills. This is the same as you experienced.
By going back to 3.78, I am reducing the overall ratio by about 3.6%. By putting 5.00X19 wheels and tyres on it, I'm dropping by 3% - about the same. I have the wheels ready to go (the old 21" tyres are worn out) so I will try that option first ($$$).Before anyone criticises me for putting 19" wheels on a '28 car, this car is a go-er, not a show-er!
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