drop in gas milage!!!!

[tershel]

hey guys.

since i put on new wheels and rubber on my fit(205/40/17)my milage seems to have drop from 430kms on a full tank to 375kms(full tank).
i had the stock 14" wheels before the big drop.
anyone know if im losing gas milage or is my speedometer going slower.

thanks for any replys

[kgb4187]

Its the bigger heavier tires. Same thing happened when I put heavy 17s on my Subaru. Went down to 16s and got alot of mileage back. (Stock size was 15)

[BKKJack]

It's probably a combination, but more attributable to the heavier wheel/tire combo. If my formulae are correct, your 205/40-17's are 2.13% larger in circumference than your stock 175/65-14's. That would throw your speed/odometer off by the same amount, relative to the stock tires. Your drop in gas mileage is about 13%. Did you have an opportunity to weigh both the stock and new wheel/tire combinations? Overall weight will be a part of the equation. Additional rolling and aerodynamic resistance from the wider tires will account for the rest.

Most important question is: HOW DO THEY LOOK?

[sillypuddy]

it's the bigger, heavier, wider tires that is sucking up your gas

-joe

[rudy]

17's? Man, I was planning on selling the 15's that come on the sport and getting some proper, lightweight 14's. The wheel just has to be big enough to clear the brakes.

[sLiVeRwOrM]

yeah, i have noticed a drop in gas after installing these 17s

[spreadhead]

Originally Posted by tershel

is my speedometer going slower.

thanks for any replys

You can use this http://www.miata.net/garage/tirecalc.html to figure the speedo thing.

[FikseRxSeven]

yes, wider tires suck up gas milage,

i switched from 225/50/16 to 285/40/17 on my rx7 and my gas milage went down by 2-3 miles per gallon on the highway, and way more in the city

[Spule 4]

Also, the standard 14" Dunlops are a low rolling resistance tire, designed with economy in mind. Fuel economy or vanity, weigh out the costs of both......

[mexellent]

Originally Posted by rudy

17's? Man, I was planning on selling the 15's that come on the sport and getting some proper, lightweight 14's. The wheel just has to be big enough to clear the brakes.

Amen to that. Although I would probably go with 15's just for aesthetics. Surprisingly enough you can get alot of BADASS tires for a 14x6 wheel. Too bad there arent very many badass 14x6 wheels.

[Bill L]

There are a few (but not many) 14 x 6 wheels at tirerack.com -- I got the Borbet CA's & have been quite happy with them, but if you want lightweight, try the Kosei TS at < 9.5 lb each.

[marokero]

I switched my stock 15's with 16x7 Spoon SW388 and Yokohama AVID H4S 205/45-16. The milage started at around 28-29mpg from my calculations after the first fill-up (I swapped in the Spoons on the same day I got my Fit). Maybe because of the heat wave, my lead foot, or both, but my current milage sits at 24-25mpg! The SW388's are pretty light at 11.9lb each, but the tires are the usual weight for a 205/45-16. But it's still much better than what my Toyota 4Runner was getting: 15-16mpg. Hopefully after my first oil change and once the heat waves goes away my milage will improve. Sucking hot air doesn't help the a/c work any more efficiently either.

[Spule 4]

Originally Posted by marokero

I switched my stock 15's with 16x7 Spoon SW388 and Yokohama AVID H4S 205/45-16. The milage started at around 28-29mpg from my calculations after the first fill-up (I swapped in the Spoons on the same day I got my Fit). Maybe because of the heat wave, my lead foot, or both, but my current milage sits at 24-25mpg! The SW388's are pretty light at 11.9lb each, but the tires are the usual weight for a 205/45-16.

All:

First, I am amazed at the MPG a lot of you are reporting, even in city traffic with full A/C, my alltime worst is 32.5 mpg. Best was 43 mpg (all highway on a long trip).

Honestly, nuts to wheel weight (and yes, Garrett knows that unsrprung weight is a factor, but not much on this).

Read my earlier post, you have removed the factory Low Rolling Resistance tires that were sent with the cars and replaced them with a performance tire.

From (forum sponsor) Tire Rack:

http://www.tirerack.com/tires/tirete....jsp?techid=29

"Now, lets explore a scenario where a High Performance replacement radial tire has a whopping 20% increase in rolling resistance over a low rolling resistance Original Equipment standard passenger radial. To calculate the potential change in mpg resulting from using the High Performance tires in place of the Original Equipment tires, we would multiply the tire's percentage of influence in the vehicle's overall resistance (15% in the city and 25% on the highway) times the High Performance tires' 20% increase in rolling resistance.

If the vehicle equipped with standard Original Equipment low rolling resistance passenger tires normally provided 25 mpg in the city and 30 mpg on the highway, installing tires with 20% greater rolling resistance would only drop fuel mileage by a calculated 3% (to 24.25 mpg) in the city, and a calculated 5% (to 28.5 mpg) on the highway. While this is a measurable difference, it probably isn't much more of an influence on real world fuel economy than being stuck in rush hour traffic a couple of times a week or being stopped at every red light instead of continuing through a string of green lights."

So a sticky tire with a bigger contact spot on the road is going to cause an impact.

If you want a sticky performance tire, then fine, but mileage will be impacted. If you have a need for these such as autocross or the like, then go for it, but it does not make much sense for running five miles down the road to the Big Box Mart....

Due to the amount of driving I do, I think if I wanted alloys, I would stick to 14" or 15" with LRR tires.

The big question is, how will these tires (LRR) do in ice and snow?

[marokero]

My Yokos can't be that sticky, they are only "high" performance all weather, not "ultra high" or better summer tires. I had the same rims on my Civic and Yokohama A520's all around. The Civic was rated at 32/37mpg, but after putting the new rims and tires I actually got 38mpg traveling from CT to NY one night. Granted, it was a manual, not automatic, and I didn't have VTEC then. If I can ease off the gas pedal and keep the revs below VTEC range, I can probably get the sticker mpg rating. But it will be very slow accelerating... I have no complaints about the milage, I know I'm to blame (the driver) for the poor mpg I've been geting out of the Fit

[FondaFit]

I did a long road trip, stayed a week and did short daily drives that included highway and lots of in-city driving and got about 32 mpg (AT) overall. On my daily, increasingly frustrating highway/stop-and-go commute, I only get about 30 mpg. Can't figure out why the difference.

[rudy]

Originally Posted by Spule 4

So a sticky tire with a bigger contact spot on the road is going to cause an impact.

Bigger/wider tires don't increase the contact patch - they merely change the shape. The total surface area is basically the weight of the car divided by the tire pressure.