polarbear
just growing older not up
Ernie you're not understanding me brother. I completely agree with what you're saying --- from stock -> larger tires you will ALWAYS see a decrease in mileage, that much I know. But you can take back SOME of that lost fuel economy with the right gearing (not all of it... like you say, that would be defeating the laws of physics). But you can bring back SOME mileage by not lugging the engine with tall tires and numerically low gearing and also not overrevving the engine with short tires and numerically high gearing (those are both very bad combo's). There is a sweet spot to get the best mileage possible for a given set of tires, even though that possible mileage will not be as good as smaller tires. This is all I'm trying to say
I understand. The "sweet spot" is easy to calculate. Look at your engine specs, and see where the torque peak is- that's the number.
Also -- when keeping constant tire size and changing gearing (like in my case) speedo calibration has no effect. The speedo on my truck takes its readings from the ABS ring (ring with teeth on it to the left of the ring gear) which has a constant diameter no matter what the gearing as (as does the ring gear). Change the gearing --- ABS ring stays the same --- speedo stays the same. Changing tire sizes? Yes of course your speedo calibration will be off and hence your fuel economy calculations, based on the odometer readings, are going to be skewed.
The speedo calibration does have one impact- accurately calculating fuel mileage. If the calibration is off, so are your calculations. In the newer rigs, tire swaps have a more serious impact on damned near everything the engine and transmission does. This is an ongoing issue in our shop with the pickups.
And for any 3rd parties out there -- we're DISCUSSING not ARGUING
Much love Ernie
And yes, this is an intelligent discussion guys.
