Actually no. Sadly I don't have my A levels Physics book with me anymore so I cant quote/post a scanned pic however I will explain.
I agree that a wider tire would increase the contact patch and hence marginally increase the rolling resistance only when the car is launched. However given the same amount of input (i.e. accelerator), fuel economy would not be affected but rather acceleration would come down. Offcourse, this loss in acceleration is not noticeable to anyone.
However, lets for argument sake, consider that acceleration indeed suffers a huge blow, and the driver has to increase the input (i.e. accelerator) to achieve the desired acceleration. This would obviously affect the fuel economy. But then when looking at the flip side, i.e. when braking, the wider contact patch means the car also comes to a stop quickly, hence the engine has to work (in strictly physics terms) for a shorter time period resulting the more fuel economy. Hence the fuel economy equations balances out due to braking and acceleration.
The only way, wider tires can have an affect on fuel economy is when you go from, lets say, 185 to 225 when obviously the mass of tire being used has increased significantly (in % terms) and hence the car has more weight to move. In this case alone, can one argue that fuel economy might suffer a little.