205/55/15 MPG

[Loren]

As has been mentioned, check your speedo accuracy and correct for it. 205/55-15's are pretty tall.

Part of the rest could be "new tire syndrome". If you like the feeling of a nice grippy tire, you might be driving a little more aggressively without even realizing it.

For reference, my car is wearing 15x7's with 215/45-15's and I still get well over 40 mpg (corrected).

[derickveliz2]

Originally Posted by Loren

For reference, my car is wearing 15x7's with 215/45-15's and I still get well over 40 mpg (corrected).

Where did you get these tires? I can't find that size. (never mind, I found them) but what is the diameter?

Thank you.

[Tonavi]

The revolutions per mile are 850 for the 185s and 845 for the 205s. That's less than a 1% reduction in gearing. This is with discount tire's calculator. "When the speedometer says you're going 65, you're really going 65.38." The difference between heights is minuscule. On some web sites, people are saying that doing wider would improve mileage because the extra width makes the tires deform less over road imperfections and therefore cause less resistance. I thought that going 20mm wider would add resistance simply because of the added contact patch. Even so, it's only a 10% increase in resistance at the absolute most.

[Loren]

Originally Posted by derickveliz2

Where did you get these tires? I can't find that size. (never mind, I found them) but what is the diameter?

Yeah, it's an oddball size. I really just wanted to try the extra width. But, with the T1R, it really didn't make that much difference. T1R's run narrow, so, the 215 is really no wider than some of the high performance "195" tires (that are often closer to 205, sometimes more) like the Dunlop Star Spec. I'm going to stick with 195/55's from here on out.

The diameter of the 215/45-15 is very short. Another reason I won't be using this size again.