Fuel Economy Test #6: Mmm... DONUTS!

[05front]

Those donuts also way a lot less

[landongendur]

@05front - they do, but to keep the weight consistent between runs I kept the large tires in the back hatch.

[05front]

@landongendur well you also where not doing 50 or 55 mph. The smaller tires were tricking the speedo.

[landongendur]

@05front - the front tires are what measure the speed (I know this because the speedometer would go up when I spun the wheels in winter). Thus putting on the tires on the rear didn't trick the speedometer.

[05front]

@landongendur oh ok. yea i kinda missed that part during the install lol

[voltairefrench]

i watched test 5 and seen the 1.4 increase with acetone.. several factors.. you said you had 5 gallons in the tank and added 2.5 or so of acetone.. your controlled test was not too controlled .. most of what i read is that your to add 2 oz per 10 gallons and when you added it i dont think you mixed it properly on most additive you add your to add the stuff first then add gas properly mixing it in your tank... maybe that is one thing you can do on your next test..

[armand1280]

That car gets twice the gas mileage of the american spec prius, and without the choking clouds of "smug".

[landongendur]

I bet a Prius would do well too at 50-mph

[armand1280]

You're probably right. But it's strange how mid to late 90's cars get better gas mileage than newer ones. That, and the European spec prius gets twice the mpg as the American spec.

[Jimmetalrules5546]

I'm not sure but i think that could be because fuel is of much higher quality in Europe apparently.

[ITBOILSMYBLOOD]

It's not too hard to realize the difference in the mileage. It's the narrower contact patch of the donut spares. The mileage would probably increase to 65 to 68 with donut spares in the front as well. Wider tires will decrease mileage, but will increase stopping power and vehicle handling abilities.

[mathleraar]

The reason the mph went up is because of less friction...the donut tyres are effectivily like ten speed tyres less surface area in contact with the road. so traction is down but fuel economy is up....

[landongendur]

I was thinking about that too... similar how a speed bicycle has skinny tires compared to a slower mountain bike.

[Morris65]

You would of gotten better results if you tested without the old tires in the trunk weighting things down...

[landongendur]

Probably. I just wanted to keep them in there so that the weight would remain constant during the testing :)

[flatlander30]

holy crap, i swear ive seen you and your geo goin around the ring road. i'm from regina as well haha, goin to school out east though. you still there?

[landongendur]

Yup, I'm still in Regina. The Geo is no longer around since a crash (see my 'living without a car' video #3).

[cadguy73]

what is that unit you are useing to test your mileage? Thanks

[landongendur]

I's called a Scangauge II. I bought mine on e-bay for around $170 and it's a pretty cool thing to use. Not only MPGs but your consumption/hour, %horsepower used, air intake temperature, etc.

[FlowingGeisha]

What's the difference between donut tires and regular ones? I only doughnuts.

[Zolar1]

Each tire has a different thread design, thus having a different rolling resistance. Also, the diameter of the tires makes a difference, not rim size.

Measure the height and width of a regular tire and a space saver tire. You'll see that a tall skinny tire usually gives the best MPG, whereas a short fat tire gives the best driveability, especially in the winter time.

[landongendur]

Precisely.

[Zolar1]

Note: I was teasing my father in law. I told him I doubled my MPG. He asked me "HOW did you do it??".

I replied, "I just filled my tires with HELIUM!" LOL

[th3s41nt]

i wanna see you run those donuts when its raining.

[GeoMetroMan91]

he totalled that car

[th3s41nt]

that sucks

[landongendur]

Yeah, I never actually had the opportunity to experience rain with the donuts. However I drove on gravel and I noticed the car liked to fishtail a lot more.

[brinbois]

ita cuz your driving slower with a donut tire... :P lol

[landongendur]

The speed in both scenarios were constant.

[123ziran]

You should use GPS to evidence your actual speed.

[TubErSkillZ]

I NEED A GEO!

[landongendur]

They're pretty cheap right now ;)

I've got something cheaper now that it's $5 a gallon in my city: a bicycle!

[TubErSkillZ]

i dont think you wanna ride a bike @ 25 below zero..

[landongendur]

I've actually did ride mine this past January and February!!! ;) Not too bad as long as I have ski-pants and a snowmobile helmet on :P

[cdltpx]

I just thought about this one the thin tires have less drag with the wind too that also plays into the equation. I knew a trucker that swore he got better fuel economy by keeping his tractor waxed and clean claiming it slid through the wind better try that theory please! Car with salt dirt on it then go wash it and wax it windows too,wax 2 times and see what the difference is I would love to have proof of that one. Some swimmers wear sharkskin suit for this.

[landongendur]

Unfortunately I can't do any more fuel economy experiments because I lost my ScanGauge during the summer of '07. That and now I'm riding a bicycle as well.

[cdltpx]

I dont know the exact number but each inch of tire on the road is so much resistance. Add up each inch and you can calculate the mpg of a vehicle prior to driving. With that said your tires are this wide for safety sake each tire is there to provide resistence which inturn = control in the event you are passed by a big rig that can suck your car into its vortex. Try stopping distance with the difference in tires vast difference you will skid just turning the wheel sharply.

[cdltpx]

I wish someone would invent a car that uses rail tires at fast speeds and could deploy a stopping device to add traction on demand this could save billions of gallons of fuel nationally. But we have morons still buying Corvettes and hummers they don't care all they think is they can't get laid with a metro. If you get chicks with your car they are sluts and you probably caught a fast disease along with that dits. If this is your mindset grow a set and get an economy car.

[landongendur]

I did notice that the traction was compromised and driving on gravel roads was brutal to the suspension with the donut tires.

[jazzmetalguitar1]

sweetness. scientifically pretty obvious, for the same reason alot of geo owners overinflate...as far as long term usage. not sure.

[landongendur]

Yeah, I thought it was similar in that it's easier to pedal a road bike fast compared to a mountain bike.

[treonsverdery]

I like your video I like science

[landongendur]

Glad you enjoyed it :)

[makihikorain]

its not really surprising at att:P the "donuts" as thinner than regular tires, and so less rubber is on the road, there is less resistance. and therefore it's easier for the engine to move the car:p

you must have a lot of time, lol i drive a geo metro convertable, i love it!

[josephdupont]

unless the angle of the car to the road is the same.. you could lose mpg.

[lmp1054]

A metro?! lol does thing are bad ass! they only have 3cyl

[landongendur]

Definitely unique, that's for sure.

[jmoyet]

thats cool. but spares (donuts) are not very good for high speeds and makes your car look like its a dump.

[landongendur]

Yeah, usually I put on the spares only for road trips to save the most fuel.

[black96fire]

Make you car look like a dump? its a metro.

[landongendur]

True, very true.

[malicea4thought]

Hey, from ma4t as GS.

[landongendur]

*waves* Hey ma4t!

[landongendur]

Yeah, apparently the all-season radials has a fair amount of rolling resistance. I do have separate winter tires for my car though.

I was thinking of getting some flat pizza pans or something for the wheel-covers (plastic trim). Thanks for your imput :)

[notvalidcharacters]

quite dramatic!

Plastic Trims = wheel covers?

[landongendur]

Yeah, I was VERY surprised.