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Stock wheels with very low front tire pressures and max pressure in rears.

As long as the overall diameter of the wheel-tire package isn't any larger on the 17's there won't be any difference in gearing.. but the difference in inertia is astounding. Remember you're taking a much larger rim and putting it 1" further from the hub... that's like 300lbs of dead weight.

You only need traction for the first gear or two.. and you can just ease off the right-most pedal to compensate.
 

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The difference in the weight of the spokes on 15" and 17" wheels isn't too much, so lets ignore that for a moment. Lets say we have two wheels, 15"x7" and 17"x7", that are of the same design.

The big difference comes in that the rim gains 3.14" .. that's a 14% increase in rim weight.. Then, by putting that weight an extra 1" out further from the hub you're increasing the effective inertia of that rim by another 14%.

Lets say the 15" wheel's inertia has a unit of = 1

1 * 1.14 * 1.14= 1.30

By increasing the size of the rim from 15"x7" to 17"x7" you've increased the amount of power the wheels soak up by 30% (not counting the spokes).

I'll be happy to show my math if someone is interested.
 
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