Winter tires reduced 10mpg

How many tanks of fuel have you averaged that over? New tyres take time to run-in as well, and one tankful isn't enough to ensure that it wasn't just a miss-fill.

 

Is this loss, the portion from the winter tires only? Or is it your total combined loss, including the portions from lower-energy-content winter fuel blends, colder ambient temperatures, increased cabin heat, precipitation on the road, and the possibility that the tires are brand new (vs. worn-in summer tires)?

Why mileage gets worse in winter | PriusChat

 

Firstly, colder weather will cause some mpg loss so winter tires aren’t the only main contributor. But yes, same effect as what I’ve experienced, installing some Michelin cross climates, I experienced 8mpg loss. Some also contributing is that any tinkering with tires, there is some minor alignment changes that probably requires realignment for most efficiency for that tire. Not sure if you wanted to hear that answer but comparing to summer mpg you will get a drastic comparison.

 

Maybe more short trips on winter too, which combined with cold temps is a double hit.

 

New tires do have mpg hit. When I put new Xice tires on my PRIME last winter, I ended up with almost 15% mpg loss from OEM Dunlop Enasave. My average with OEM tires during winter was 53.2 vs with new Xice tires 46.5. This comparison was from the first winter without winter tire and second winter with snow tires, so all the conditions are accounted for except year to year variation in weather during those two winters. However, after single-season and ~5K miles on the snow tires, this season with the same Xice snow tires I have been getting close to the same mpg as OEM.

 

Out of curiosity, what was your tire pressure, before vs. after the switch?

 

Don't know about OP, but mine was set 38 psi cold both front and rear. I adjust it seasonally, so try to keep this 38 psi at the coldest temp in the morning. Still, I sometimes see my tires go down to 34 psi on a very cold morning.