18x8 wheel mpg performance
 

Just bought an 06 LT about a month ago with the 17" stock chromes still on. Looking at some solstice wheels.

I was wondering for those of you who have switched to the 18x8s what the effects on your fuel mileage is?

I ask because I just switched wheels/tires on my wife's 05 vibe from stock 16's to 18x8's and had a noticeable drop in mileage on that car. Not sure if it's the 1.8L in her car that doesn't like the added rolling resistance, or if it's the kumho tire compound (maybe soft?), or both, that has caused this effect. Just wanting to do some research on the hhr's before I pull the trigger on a new set of shoes.

Sorry, I didn't check it before I switched to 18"s. Mine averages 25.5 carrying 300lbs all the time if that helps any. But I only run 28lbs in the tires, like the soft ride.

You will see a drop in gas mileage for sure. Possibly substantial. Are you planning on using this as your daily driver, modifying it into a show car, or both? If it's going to be your daily driver, you have to ask yourself what your motives for making the swap are. Are you truly pushing the car hard enough in the corners to need the extra grip? Are you doing it strictly for the aesthetics, and if so, is the look you're after worth the added fuel expense?

1 possible solution could be to keep the stock wheels and tires and buy the show set. You could simply swap them out depending on the occasion. Just my 2 cents for what it's worth ;)

I just brought this up like last week lol but depending on ur engine size (mine a 2.2) u will feel a lag in acceleration and mpg will go down..mine is a daily driver also. I have the stock SS wheels with new michelin pilot sports

I went from the stock 16" alloys to 18" Cobalts. Gas mileage didn't change one bit. The stock forged alloy's are lighter than the stock cast alloy's.

I am running 18" Solstice wheels and I live in the 29.7 - 31.2 mpg range driving 150 miles per day. Some two-lane country road at 60 mph and some interstate at 74 mph.

"you doing it strictly for the aesthetics, and if so, is the look you're after worth the added fuel expense?"

This is the question that I am pondering. I don't like the looks of my 17's, but really love the soltice 18's. Maybe there is another option of 17-18" wheel that is similar to that of the solstice but in a 7"? but Dont want to make the swap on a daily driver if it absoultely kills the MPG. Driven it 750 miles since I purchased, I get the following for milage with the 2.4:

In town: 25.5
60-65 mph: 34
75 mph: 29-31

If it's 1-2 mpg I can live with it, but that vibe I referred to in the Initial post dropped 5 mpg on the hwy. In town doesn't seem to be as bad.

Sorry if this is a duplicate post. I tried searching for some key words and didn't yield the result i was lookign for

this was my experience as well

Ours is a 2.2. Switched from steel 16s to SS/SC Cobalt wheels. No difference in anything except for speedo, because it had 225/45/18s on them. New tires will be 225/40/18s, so speedo should be happy once again. :twothumbs:

I don't see how changing from 17" to 18" whees will drop mpg "possibly substantial".

As you probably already know
Different tires will effect gas mileage
Acceleration an handling and of course ride quality and appearance.
They will also effect mpg
Due to
Shorter or taller tire.
Heavier or lighter rims and tires
Wider or narrower tires
Manufacture and model of tire..
Here is a tire calculator that I use often.
http://www.dakota-truck.net/tirecalc/