did the factory change the computer settings for the differences between the 16 and 17 inch tires. The aspect ratio has changed but still one does 8 rev per mile more with 17 inch tires and the speedometer would be off along with the odometer(10miles per 1000 miles...not much but still). This would also change the true mpg if the computer is set for 16 inch tires and not 17 even though they are close.

 

No, the computer does not change for tires.

Going from 16" wheels to 17" wheels doesn't matter as long as the tires diameter is unchanged.

For example, I went from a 235/60-16 tire/wheel package on my Tucson to a 235/50-18 tire/wheel package. The original 235/60-16 tires were 27.1" tall and the new 235/50-18 tires are 27.3" tall. That equals 5.4 fewer revs per mile or a 0.7% difference.

I'm assuming you are refering to the 2 available tires/wheels on the Touring. The difference between the 205/55-16 and the 215/45-17 wheels/tires are small. The 16" tire is 24.9"tall and the 17" tire is 24.6" tall. That equals 7.7 more revs per mile or a 1% difference.

A 1% or less difference is acceptable. Most uncertified automotive speedometers and odometers are not exact anyway and are within a 1% error range.