2007 C280 Want to get bigger wheels....
 

Anyone can tell me if I can get 17' on my C280? Currently have 16's let me know!

poorman
 

I have a 2005 C240 that came with 16" rims. I went up to a 18" rim and I have not had any problem with the car or the ride.

Will the mileage be effected when I get bigger tires?

I too went from 16" to 18" on my C240 with no issues or change in mpg. The size recommended for my 18's in order not to affect the speedo calibration was 40 series on the front and 35 series on the rear. The width depends on the rim width. There is more road noise with the lower profile tires however.