I am going on a road trip to Cali and I was told that my 17's will get better gas mileage than my stock 15's. I know 15's will get me better times at the track and street but I thought the rolling diameter of 17's would yield me WORSE gas mileage than 15's. My friend told me that the inertia of the 17's and that fact that they travel further per revolution would help. Also he said that although 15's will get better times, 17's will get higher mph's on a drag strip. Can you guys clarify?

 

I would think the weight would have to be a factor to consider. If they are heavier there is more load for the engine to pull thus would make for worse gas mileage, but I'm not sure about anything else.

 

the 17's are almost the same weight as the stockers +- 1 lbs

 

best way.. road test for a week. Put the 17s on one week and see how many miles ot a tank, then the 15s the next week and see how much. But DONT drive agrresive...

Or just put the stockers on as thats what the car came with gearing wise...

 

17" will give you a smoother ride, and since you're making fewer revolutions I would think they would offer a little better mpg for cruising.

 

what's the total diameter of the 17" wheel + tire vs the 15" wheel + tire. The 17 will have more inertia but I doubt much. Keep it out of vtec and you'll get great mileage no matter what. If you really want good mileage, install cruise control.

 

wouldn't that depend more on the tires he's using? I would expect 17's to be a rougher ride, actually.. especially on a stock suspension.. regardless of suspension though, smaller/stiffer sidewall = rougher ride..

although he might be making fewer revolutions, he really shouldn't be.. if he plus sized the proper way, then the tire's would be smaller, making the overall diameter of the 17s with tires the same as 15s with tires(lower profiles on the 17s to compensate).. if he DIDN'T plus size the proper way, then his odometer and speedometer are now incorrect.. in which case it might appear that he's getting better mileage, but it's really not since the actual distance traveled would be different from what the odometer shows..

this is also why i wouldn't buy a car if I knew somone had big wheels on it, like 17s or 18s.. the odometer is most likely incorrect..

edit: my grammer needed a fixin



[Modified by mstewar, 4:45 PM 8/12/2002]

 

This thread is making me sick...
There are so many fallacies here I don't even want to try correcting everyone.

I realize this is a place for learning but it irks me when people tell other people totally incorrect information.

 

tires.

 

I've got 205/40ZR-17's..

 

then you have plus sized correctly, because your speedometer is only .1% too slow(negligible difference).. in this case, weight of the wheel/tire combo will be the main thing making a difference between the two sets.. i wouldn't worry about it..


this site is good for doing the plus sizing calculations and seeing if your speedometer is off or not.. just plug in the stock sizes and what you currently have..

http://www.miata.net/garage/tirecalc.html


have fun on your trip..


[Modified by mstewar, 4:49 PM 8/12/2002]

 

Who cares about gas mileage??

 

In this particular question, it just depends on the weight and diameter of the wheel/tires. Stand your 17's with tires and your 15's with tires next to each other, and the bigger one will have less rotations per mile, which will give better gas milage because the motor will be rotating at slightly, and i mean slightly, slower speed. However I dont even think the gas mileage difference would be noticable in the end so I wouldnt even bother.

 

tornado fuel saver

 

Go the speed limit, or below! LOL!!

Oh. yeah ... rim/wheel weight won't make a difference at a constant speed, only under acceleration.

Though you could put extra air in the tires to lower the rolling resistance.


[Modified by Zygspeed, 5:33 PM 8/12/2002]

 

a Yugo?

 

if we cared about gas mileage, we'd all drive a Geo Metro

then again, there's probably some schmuck out there w/ a Metro Type R

 

Now why you gotta be cappin' on a Metro? Just kidding.

On teh Autopedia website there was a dyno chart that also included a fuel consumption (lbs/min or gals/hr or something) and the lowest point happens to be at around 4200rpm...which is roughly 80mph (I think)...keep it at that with easy starts/accelerations and you can hit over 30mpg with properly inflated tires, clean air filter and good plugs. If you wanna live dangerously tailgate, er, draft off anotehr car. I wouldn't recommend that.

-Geo

 

This is worth trying behind big semis or uhauls for a bit, def good *** gas mileage, just be careful.. hehe