The sticker on my dodge says it should have 17 in. tires but it can with 20s. Is that right. Also what did dodge do to the hemi to get such higher gas mileage on the 2015 than say an 04?

 

20's are an option. 10yrs of technology.

 

The stock tire is not 17", it's more like a 245/70x17, which is about a 30 1/2" tire. The 20s are probably a 275/60x20. Wheel size has no bearing on overall diameter. A larger diameter tire will provide better highway mileage at the expense of off-the-line jump.

Anyway, MDS probably had the biggest affect. That and computer refinements.

 

Vehicle manufacturers are continuously working to improve efficiencies. 10 years is a long time. Pretty much everything is better than it was 10 years ago.