[Power Hungry]

I was merely reflecting on the affects of acceleration, not sustained movement. You are correct that once it is moving it takes much less effort to keep it in motion.


For the sake of discussion, here's one thing to ponder; Let's assume you go from a 31.5" tire (average stock height) to a 35" tire (most common upgrade) while keeping the same 20" rim.

Surface area of the wheel = 314.159 square inches.
Surface area of a 31.5" tire assy. = 779.311 square inches.
Surface area of a 35" tire assy. = 962.224 square inches.

31.5" tire alone = 465.152 square inches.
35" tire alone = 647.954 square inches.

This is means at a minimum, the 35" tire has roughly 39.3% more surface area and presumably 39.3% more mass (or weight, whichever you prefer).

I know this doesn't seem like much, but when you figure in the fact that a 35" tire would have a thicker sidewall to allow for the taller sidewall height, is usually wider than the average stock tire, and often has an aggressive tread pattern which may add to the total mass, the average 35" tire may be more in the area of 60% greater mass (weight) then the average stock tire. Throw in some "bling" wheels and the ante just went up.

I can't remember the exact figures, but when we swapped out the stocker tires on the '06 F-150 for a set of 35"s and new wheels, the 35" wheel and tire assy. was almost TWICE the weight of the stockers. Of course, the stock wheels were the standard Ford 6 spoke variety and the replacements where solid "western" type with bead-locks, which I'm sure added a bit of weight.

One thing to note as well... After spending years as a mechanic and changing tires of all sizes, a 35" tire assy. will often take up to twice as long to spin up to speed (150 RPM) for balancing when compared to a standard stock tire assy. will. This nice thing about this comparison is that the HP of the electric motor (usually around 2HP) doesn't change and there's no transmission or differential to factor in. The ONLY difference is the wheel assy.

Of course, I'm not even getting into the torque factors due to the larger radius of the tire and the energy needed to move the mass at the edge of the new tire radius as those calculations are frankly a little more involved than I care to even think about right now.

Anyway, just food for thought.