Josh

Since I switched to my 195/65QR15 Bridgestone Blizzaks, I've gotten MUCH better gas mileage (25-26MPG vs. 22-24.5MPG). They're not a low rolling-resistance tire (like a Michelin Energy), and the roads have been wet, dry, salty, icy - you name it. They're also better balanced than the 225's I put on before changing to winter tires (morons scraped my wheels AND did a crappy job balancing), but the 225's yielded unusually low MPG numbers...<p>-josh<br>98.5 2.8qms+Blizzaks and plastic wheels covers

Rutgerb

Of course wider tires cause worse gas mileage.<br>In theory gas consumtion can rise 5-10% with wider tires. They influence aerodynamics in a negative way. Remember the aerodynamic champion, the Audi 100 of 1983. The 1.8 liter model with 175 mm wide tires had a Cw of 0,30, the 2.2 liter five cilinder with 185 mm wide tires a Cw of 0,32.

David Hess

While wider tires increase performance in most cases they also give lower gas mileage figures. Another reason why you have lower gas mileage is that the 225s you had were probably a very soft high performance tire, the winter tire is harder. Harder tires don't hold on to the road as good but they deliver better gas mileage. Another annoying thing that may increase with a wider tire size is tire noise. <br>Dave Hess<br>98.5 2.8 QSTip

Ray Calvo

The outside diameter of the Blizzaks could be larger than your 225 summer tires, causing engine to turn at a lower speed at given road speed, thereby acting like a lower ratio differential. Have you checked speedo error before and after the tire change? Your speedo could be off now while it was closer to true before, or vice versa.

pdw

by their very nature, as compared to wider tires. They are also more aerodynamic(tires effect drag a surprising amount).<p>These are both reasons that racing bicycles use very narrow tires.

steveW

suspect that lower overall speeds are contributing to better gas milage. My gas milage improves 3-5 mpg going from 80mph down to 65 mph.