Ever since I put my 20s on, my avg mpg dropped from 19 to 16. Is that normal or do I need to recalibrate something?

 

Probably want to compare the weight difference between the 20's and the stock wheels you took off.

What brand/model wheels?

 

XIX X05 they're machined aluminum wheels, so they shouldn't be much more than stocks
Here's a picture of them:
http://www.elementwheels.com/prodimages/x05bm.jpg

 

You just increased your rolling resistance by a lot going to 20" wheels. City mileage will suffer as a result. 20% of your fuel goes to overcoming rolling resistance from tires. The bigger and wider the tire, the more rolling resistance.

 

You know what, I don't like your tone sir! Damn you and your logic :/

 

Rotating inertia has greatly increased, even if the wheel weight stays the same.

 

gotta pay the cost to FLOSS!

 

+1

Wish I has the extra coin to buy forged 19's and reduce some unsprung weight

 

With that logic, it would mean if I switch from my stock 19" rims to stock 18" rims my mileage would increase???

 

maybe down to 17 will make a noticeable difference.

 

i get about that with 22s.

 

I average 23-25 depending on hwy or not with my Vossen 85 20"s.

 

It costs to be a boss, you have to pay the tax, lol.

 

I am a fire flame spitter....

 

It's called angular momentum. And it increases as a square of the radius from the center. The wheel's overall weight pales in comparison to the amount of energy required to spin the wheel.

In other words, you may have a wheel that is even lighter, but has a bigger radius. This wheel could easily demand more energy to rotate than that of a smaller radius.

 

My stock 18s give me 25 to 30 mpg in a mix of driving. That's more important to me than the oversize 22s. it takes alot of torque to overcome those wheels and your 0-60, 1320 time also suffer.