I decided to use snow tires this winter season since I had a few puckered incidents last season and I chose to use 15” wheels with Blizzak WS90 on my 05 R53. We haven’t had any snow yet and I drive 60 miles a day and noticed I going through gas line crazy! I was averaging 23-24 mpg and now I’m getting 19-20 mpg. Is that normal for snow tires?

 

Perfectly normal. Snow tires are designed to grip the road better, which means more rolling resistance.

 

I can't tell any difference as long as the nominal overall diameter is the same.
I run 205/45 x17 & 185/65 x 15 & there is less than 1/4" difference. In fact, the snows are a tiny bit larger, which will have a tiny effect on the speedometer & therefore the mpg calculations.

 

yep exact sizes that I have as well.

 

There’s no snow in the upcoming forecast so I’m switching them back for now.

 

I think In your case, your winter wheel set is also much lighter than your summer, which will offset some of the mpg loss due to winter tires. I would expect any mpg difference to be a wash in your case.

 

well it didn’t it went down drastically. I figured it would go up since the wheel- tire combo is much lighter that the 17” setup??

 

Winter gas?

 

Colder weather drops mileage BUUUUT adds power 🙃

 

I typically get around a 10% drop in mileage with snows on (30mpg-27/28mpg). YMMV,

 

I average about 24 and it dropped to 20. I took them back off and will wait till they’re calling for snow then I’ll swap them back on.