Hi, I'm new to this site but found a lot of info on here before about buying non run flat tires. I just got my new Goodyear high performance tires on my car about 3-4 weeks ago and have noticed a decline in my gas milage. At first it started with being off maybe 20 miles but is now off by 50 miles! Is this a tire issue or is this something that is way beyond tires? I'm also having a problem with lag when accelerating from a stop. Happens maybe once a week. Could they be connected? Any experience/advice with this issue is greatly appreciated!

 

New performance tires and decreased gas mileage may have direct causation with the excessive use of the right foot. Only more mileage, as in a couple tanks will you be able to tell 'statistically'.

Lag or bog, I experience this, mostly with the combination of AC load and dead stop and a incline without revving into it hard enough. The trifecta of torque killing.

 

Are your new tires the same diameter as your old ones?

 

Ahhh I am an idiot, you are talking about miles driven not MPG.

Possibly just the difference from a worn tire to a new and therefore slightly larger diameter, could be. The difference between a 205/45 and a 40 is about 2% speed difference in the speedo, and going from very worn to new could be that much.

 

Thanks for the responses. The tires are the same size and yes, perhaps I have been driving it a little bit different with nice fresh tires but I couldn't believe how quickly I went through a tank of gas. Seems odd. I know I was getting originally getting about 29 miles/gallon. Curious to see what it is today when I fill up.

The lag sounds like what you are talking about too. I have to give it a lot of gas to get going and it slowly goes. Then, once I am going its as if the car kicks into high gear and takes off.

Thanks for the help!

 

Both really. I usually can go 300+ miles before needing a fill up and last night I had only gone 250 miles. However, the last time I filled up I checked my MPG and it was 28.

 

It will depend more on the tire design rather then if they are new or old.
If they were the exact same model tire, it won't make any noticeable difference, if both tires are in good shape and inflated the same.
This may depend on the tire model too, as certain higher end tires have different rubber formulation layers to make up the performance differences due to tread depth as the tire gets older.

If you change to a different model tire that has additional technologies that affect mileage then that will make the difference.