I was thinking of going from 17" wheels to 18" wheels on my car (retroactively). However, someone at work said that this would show up on carfax (since the original car did not have 18" wheels) and that would negatively impact resale value. In addition, the car would need to be recalibrated for a larger wheel as that would impact the speedometer, suspension etc and may be a bigger job than I'm thinking.

Thoughts on this? And lets for the moment pretend that this upgrade were free.

If you stay with the original factory sizes, the 18" wheels and tires will have no effect on anything since the aspect ratio remains the same. A simple upgrade to larger tires should not have any adverse impact on resale value ... and it has nothing to do with any CarFax report.

Stan is right that you can go from 17 to 18 (or the other way) if you properly size the circumference to match. 1010tires.com has a great calculator which shows the different effect of different sizes. It's worth spending time with.

http://www.1010tires.com/Tools/Tire-Size-Calculator

However, before taking on the pros (style) and cons (just about everything else dynamically, although a not resale value loss) of larger wheels, here is an interesting recent thread to read start to finish.

https://mbworld.org/forums/c-class-w...8-vs-19-a.html

Ok thanks all. It does appear as though the difference is negligible if I'm reading the site correctly (although I had to use the 2014 model). I have the regular C300 (w/ premium plus) so I don't think the 18's will still feel comfortable. Is there a difference between the wheels/tires used the AMG style 5 spoke vs the standard 18 inch 5 spoke option (besides looks)?

Sizes are the same for any 18" tire setup regardless of the trim package.

I have 5 spoke 18's on my base C300, and am currently driving a loaner which happens to be a C300 Luxury with the 17's. The difference in ride comfort between the two is negligible. The Sport/AMG suspension or the 19's have a much greater effect, based on my experience, on the ride than just going from 17's to 18's.

Should have proofread my comment. I meant to say that the 18" wheels will still likely feel comfortable as I have the regular car w/o sports suspension. We will see.

Any update on your car Stan?

Not a word this week, but I expect it be ready in a few days based on what I was told last week.