Getting new tires/wheels. Should I go smaller?
 

2007 Honda Fit Sport.

Currently on stock 15" rims and 195/55 tires. Coming up for a tire change, I am wondering if I should get 14" rims? I can get some 14" rims (2002 Civic Hybrid) and 185/70/14 Michelin Destiny tires. Or stick with my current rims and get the same Destiny tires (185/65/15). What do you think? Will I see a noticeable amount of MPG gains?

What kind of driving do you do?
How much do the tires weigh?
How much do the wheels weigh?
Are the new ones going to be lower rolling resistance?
Which wheels are easier to equip with aero covers?
Will 14's fit over your brakes?

First, changing tire size has a small affect on fuel economy - all other things being equal.

What has a much,much bigger affect is careful selection of the tire itself - up to 60%!

What also has an effect - albeit on the same order as the size change - is going larger (because it is in essence a size change). The tire size you have is not very popular and some folks have commented about the difficulty in finding a good selection in that size. Going larger can solve that particular problem. Just be aware that there are clearance limitations with regard to the fenderwell, the strut, and the wheel width. Unfortunately, I know of no one who publishes a chart showing how big you can go, but rule of thumb is 2 sizes.

Also be aware that going larger will change your speedometer and odometer.

Frankly, I wouldn't waste time thinking about going to 14". Stick with the 15" and use a larger size.

I'd suggest staying with the same rims and adjusting the tire size if you want... but if you do go to a smaller size rim, let me know - I might be interested in those Fit rims.

From what I have heard 14" wheels are on their way to retirement. Id stay with the 15's and just get a size or two bigger/smaller if thats what you want. Keep in mind load ratings.

1.DIAMETER of the tire is what is important. if you are decreasing the overall diameter of the TIRE you will hurt mpg.
2. you gain a SMALL amount with a smaller/lighter? rim. because you are moving the MASS in. Given that the tire is at least the same diameter.
3. I have increased the tire diameter on both my vehicles using the stock rims and got better mpg.

Many better choices of tire with 15 inch rims. Going smaller may cause problems if you do not have enough clearance with your brake caliper.

regards
mech

14 inch wheels are on their way out.
Soon you will only be able to get 14s made in china that will only be "DOT approved" because they carved it into the tire mold.

The only time smaller tires will get you better fuel economy is if you regear the transmission or differential to a numerically lower ratio.

You cant just expect to put smaller cheaper wheels on and get better fuel economy.