Hey, I was wondering if this seems right.

On my 6th gen EX, I had 14" steelies running Yokohama 195/55/14. I used to get like 32 mpg if I don't drive hard.

I bought some dudes Si 15" OEM alloys which had Falken 195/50/15 on them. The tires were bad so I bought new Yokohama AVS ES100 tires 195/50/15.

Suddenly my gas mileage is like 27 mpg. What the heck?

Ok, I know that the circumference of the 14" was smaller than the 15" by about 1% (odometer not changed). The alloy rims are supposedly lighter than the steelies, and I didn't think the new Yoko's are that much heavier than the old ones. Does -5 mpg sound right? This sucks. I'm not even driving it hard.

 

Bad alignment? Low tire pressure? :dunno:

 

is this consistent or were you driving at high rpm with the 14s

 

Your weight may be less now, but with 15's your rotional mass is further out from the center of the hub, thus needing more energy to turn the wheel.

 

I went from 185 tires on 14s to 205 on 16s and the decrease of my gas mileage is not noticable at all. I don't even think it went down.

 

As far as alignment goes, when I bought the tires the company that sold and mounted them also did an alignement... so supposedly my alignement is now "better".

As far as air pressure goes, the 14" was at 30/29 psi and now the 15" is at 33/32 psi.

Nothing else has changed. Driving conditions the same, everything.

This is really wierd. (and unnecessarily expensive)

 

maybe you should get some 13's and make it go up even more. h:

 

I would've thought tire pressure first off, but I dunno.

 

I'd say alignment since that's what changed and can really effect something like that. If your toe-in/toe-out is off then you're working against the tires when you drive, causing your motor to work harder and use more gas. That's my diagnosis.

 

for every 5mph over 60mph you lose 1mpg. learned that from car and driver.