ZUKIWORLD Online | Suzuki 4x4 Editorial and Forum
ZUKIWORLD Discussion Forum => Suzuki 4x4 Forum => Topic started by: Digger on August 18, 2005, 08:33:51 PM
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I must be having a brain block or something, ::) but I'm having trouble figuring out comparative milage numbers. Running 215/75/15's, I'm getting around 22 miles per gallon according to the trip odometer and how much gas it takes to refill the tank each time. Running 33-10.50/15 Swampers, I'm getting around 17 miles per gallon when figured out the same way, by dividing the trip odometer by the gallons to refill. I know that when I'm running the swampers, I'm moving 15 miles per hour faster than the speedometer tells me I'm moving when it reads 60MPH. So how many miles per gallon am I getting running the swampers when corrected to directly compare to the 215's? ???
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Actually the 17 MPG sounds about right.
If you really need to know, you need to
go the same # of miles, like on a trip of
say 200 miles, once with the Swampers
and once with the 215s, then refuel and
divide your gallons and miles
Other than that, if you can figure that for
every 100 miles you go say 15 miles farther
you could use the higher corrected # to figure
your MPG, but in the case you show here, you
didn't include any milage #s to be able to get
an estimate of your true MPG
Look up the gear calcs on the web site
(check the bottom of my post) and figure
your true mileage travled and gallons used
Wild
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Every time I refuel, I fill the tank the whole way and reset the trip odometer. At the next fill-up, I take the trip odometer's reading and divide it by the number of gallons needed to refill the tank. That's where I got the figures of 22 and 17 for the different tire sizes. However my problem is figuring out the difference in distance travelled between the 2 sets of tires. I don't feel it is quite right to compare the 22mpg and 17 mpg directly against each other because the 17 isn't accurate. When I'm running on the swampers, I'm travelling further than the odometer reads, but by how much, I'm not sure. So if I'm actually travelling further than the odometer is telling me I travelled, I'm actually getting more miles per gallon than the odometer is telling as well, right?
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Right, that's why I suggested you
go on a trip with both sets of tires,
same distance and speed, then
compair miles and gallons
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Let me try to give you a rough rule of thumb...
According to my calculator....
- P215-75-15...............27.7" diameter.........7.24' circumfrence
- 33-10.50-15..............33.0" diameter.........8.635' circumfrence
You travel 19% farther per indicated mile on the 33's than on the 215's
so your 17mpg on the 33's is more like 20mpg
Caution...you are going abouot 19% faster and farther than indicated on the speedo compared to the 215's.
Zag
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According to my calculator....
- P215-75-15...............27.7" diameter.........7.24' circumfrence
- 33-10.50-15..............33.0" diameter.........8.635' circumfrence
You travel 19% farther per indicated mile on the 33's than on the 215's
so your 17mpg on the 33's is more like 20mpg...
That's what I was trying to get to. I just couldn't come up with circumference figures, I kept coming up with area instead of circumference. ::)
So, now to compare the corrected figure of approximately 20MPG on the Swampers to 22MPG on the 215's(which I realize is kinda low, but calipers are dragging a little more than normal) I can see that a 2MPG gain is hardly worth the weird looks I'm getting from people by running around town in a rig with 6+" of total lift on stock rims/tires! Guess I'll swap the swampers back on tomorrow morning! LOL!!!
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I would be willing to bet those 33s are closer to
32" which is a 13% increase in speed, but I still
need some gallons and #s to give you an accurate
MPG with the bigger tires
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which Swamper is that ??
I might be able to look up the #s
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33x10.50/15 Swamper TSL Radials on 15x8" Jackman welded steel wagons.
I didn't keep track of the trip odometer reading and gals used for each fill up past the fill up, I just figured out the milage for each tank of gas, then averaged those figures to get 17 and 22...
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Naw, I found it 32.7" tall (dia)
so thats 15% higher, so in 100
miles on the Odo you get 115
miles, and at 60 indicated you
are going 69.5 MPH and at 70
you are going 81 MPH be careful
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Even at 15%, it's still approximately 19.55 MPG on the Swampers compared to 22 MPG on the 215's. A total gain of 2.45 MPG when rolling on the little tires. Still not worth the silly look IMHO! LOL!
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More that one dude has about broke his neck
trying to get a second look at the tires on my Kick
At least 2 of them on the freeway, they caught a
glance and had to look back out of the window to
make sure they weren't seeing things ;D
I like it
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Yeah, but that's running bigger rubber than stock, right? I got people looking twice and laughing at my really tall Tracker running little tiny tires... LOL! I liked the attention of running the 33's a lot better! LOL! :o ;D
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Ohh ya 33-13.5 LTBs on 2.5 BackSpace wheels
looks like a mini monster truck coming down the road
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Ohh ya 33-13.5 LTBs on 2.5 BackSpace wheels
looks like a mini monster truck coming down the road
LMAO!!! ;D :o ;D
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(http://wildcatent.freeyellow.com/suzuki02.jpg)
Or my favorite
(http://wildcatent.freeyellow.com/suzuki-rock.jpg)
Here's my buddy sliding off of the rock, and the real
angle this rock sits at, my pic makes it look like an
easy climb, but he never could get on it with welded
front diff and a locker in the rear on 38 Swampers ;D
(http://wildcatent.freeyellow.com/OffRoad16.jpg)
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According to my calculator....
- P215-75-15...............27.7" diameter.........7.24' circumfrence
- 33-10.50-15..............33.0" diameter.........8.635' circumfrence
You travel 19% farther per indicated mile on the 33's than on the 215's
You don't have to work out the circumference, its all directly proportional. 33" is 19% bigger than 27.7" (33/27.7 = 1.19 or 119%)
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Lets make this real fun for the days that you have absolutely nothing better to do ( such as watching the grass grow)
Put on the small wheels. put truck on straight away flat road with no traffic to bother you, such as a parking lot.
put a chalk mark on the sidewall of a rear tire where it points straight down at the road.
continue the mark onto the road as a start point.
roll the truck forward with wife or girlfriend (but not both) walking along the side of the truck.
count ten revolutions and stop with the chalk mark pointing straight down again.
mark the road at that point.
measure the distance from start to end in inches.
Write it down.
change to larger wheels.
repeat process of marking and measuring.
write that down
Take wife or girlfriend out for a beer
while having beer do calculations (I hope you remembered to bring the calculator )
take number of inches in your first measurement.
divide by ten. thats your rolling distance per revolution accurized by a factor of ten.
take number of inches in a mile and divide by your rolling distance per revolution figure.
(I'm not going to give the inches per mile figure here that would make it too easy and take all the fun out of this)
result is your number of revolutions per mile.
take the measurement of your second tires distance and divide by ten to get your second accurized rolling revolution figure.
take the revolutions per mile from the first calculation and use that to multiply the second rolling distance figure from your larger tires.
the result is your true distance traveled on the larger tire.
now heres where the wife or girlfriend part really gets important!
Say to her "honey I know you are much smarter than me cuz I failed math in school while you got straight A's cuz I was daydreaming about four wheeling all the time in school"
then get her to figure out the percentage of difference in travel distance and calculate the mileage difference. She can then do all the other math to help you figure out true distance covered, true speed, gas mileage, etc.
Then go mow the grass or whatever to pay her back and keep her happy cuz you owe it to her!
by the way this only works if you know the true mileage you were getting on the small tires.
Now wasnt this fun?
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that's a lot of work to come up with the same percentage you would get by just dividing the 2 tire sizes ...
using the numbers rhinoman used ... 19% means you have gone 19% farther on the 33" than you woulda on the 27.7". If your speedo was accurate with 27.7", then with the 33" you're going 19% faster. Similarly, you would have gone 19% farther on the odometer. To figure gas mileage, take the odometer reading multiply it by 1.19 (this adds the 19%) and then divide by fuel quantity used.
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Lets make this real fun for the days that you have absolutely nothing better to do ( such as watching the grass grow)
Put on the small wheels. put truck on straight away flat road with no traffic to bother you, such as a parking lot.
put a chalk mark on the sidewall of a rear tire where it points straight down at the road.
continue the mark onto the road as a start point.
roll the truck forward with wife or girlfriend (but not both) walking along the side of the truck.
count ten revolutions and stop with the chalk mark pointing straight down again.
mark the road at that point.
measure the distance from start to end in inches.
Write it down.
change to larger wheels.
repeat process of marking and measuring.
write that down
Take wife or girlfriend out for a beer
while having beer do calculations (I hope you remembered to bring the calculator )
take number of inches in your first measurement.
divide by ten. thats your rolling distance per revolution accurized by a factor of ten.
take number of inches in a mile and divide by your rolling distance per revolution figure.
(I'm not going to give the inches per mile figure here that would make it too easy and take all the fun out of this)
result is your number of revolutions per mile.
take the measurement of your second tires distance and divide by ten to get your second accurized rolling revolution figure.
take the revolutions per mile from the first calculation and use that to multiply the second rolling distance figure from your larger tires.
the result is your true distance traveled on the larger tire.
now heres where the wife or girlfriend part really gets important!
Say to her "honey I know you are much smarter than me cuz I failed math in school while you got straight A's cuz I was daydreaming about four wheeling all the time in school"
then get her to figure out the percentage of difference in travel distance and calculate the mileage difference. She can then do all the other math to help you figure out true distance covered, true speed, gas mileage, etc. ÂÂ
Then go mow the grass or whatever to pay her back and keep her happy cuz you owe it to her!
by the way this only works if you know the true mileage you were getting on the small tires.
Now wasnt this fun?
Ah but you forgot that the tyre swells with speed so you need to repeat the chalk mark test at lots of different speeds. Then to work out how far you travelled you have to calculate the distance travelled for each speed at which you drove and for how long you drove at that speed.
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Ah but you forgot that the tyre swells with speed so you need to repeat the chalk mark test at lots of different speeds. Then to work out how far you travelled you have to calculate the distance travelled for each speed at which you drove and for how long you drove at that speed.
Yes, but to figure out this test at different speeds, wont I need a much faster wife or girlfriend? ;)
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Ah but you forgot that the tyre swells with speed so you need to repeat the chalk mark test at lots of different speeds. Then to work out how far you travelled you have to calculate the distance travelled for each speed at which you drove and for how long you drove at that speed.
Yes, but to figure out this test at different speeds, wont I need a much faster wife or girlfriend? ;)
Oh yeah, a little running is required ;D. There should have been a couple of smilies after that statement but all I got was an error message. If they're really quick then they can also draw a chalk line across the tyre and check your pressures at the same time ;D
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Well, I just got in from the driveway where I swapped the Swampers back on. 2 MPG just wasn't worth it to me. I'll un-modify Silver and give him the stockers. He can be my runabout rig...
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Ok my turn......if you have a handheld GPS, or can buy or borrow one.....use the trip odometer feature on it and get REAL numbers instead of calculations. A GPS will tell you how far you have gone just like your odometer on your rig. It will also tell you how far your speedo is off...and is fun for lot's of other stuff too 8)
If that isn't an option......do what they said ;D
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I really thought my idea was pretty clever! Probably would have been real neat to see it on video to boot!
guy marking tires $35
guy convincing girlfriend to help $50
guy and girl doing calculations in a bar over a few beers $100
Girlfriend running alongside truck counting tire revolutions PRICELESS
for everything else theres Master Card
I went from 205's to 235's and used radar to check for accurracy. on 205's I was dead on for speed and now on 235's I'm going 2 miles per hour faster at 45mph indicated than I was on the smaller tires. (By the way the variance in speed increases with higher speeds)
So now when I get 22 miles per gallon average I'm actually doing about 5% better, so really about 23 MPG! ! !
Boy this has been a very educational thread for all of us gear heads and fat tire muddy trail runnin wheelers! ! !
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Well, I figure that once the tires are rolling, the bigger tires are easier to keep rolling and roll over road imperfections easier than smaller tires, so the bigger tires get better mileage on the open road. They get worse mileage when climbing up hill or accelerating from a stop though... I'm sticking with the 33's though. They SO much better on there! LOL!
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all I know is that I changed from 205's to 235's and then my wife in her corrolla was driving in front of me one night ..... 10 kms an hour diff at 100 kms/h was alot more than the 4 kms/h that the calculator on one site told me....and whether I drive nice or hard is a difference of 400kms a tank uncorrected or 300kms a tank uncorrected.....? :-\
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..... 10 kms an hour diff at 100 kms/h was alot more than the 4 kms/h that the calculator on one site told me
Are you working on actual tyre diameters or just what the makers claim? Tyre diameters vary quite a bit from what they should be and even more when rim width is different from the one the tyre manufacturers took their measurements on.
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I have found this thread very interesting. So when I'm running a set of 205/60/r15s (my free set of winter tires) what exactly is it doing to my rig? Sorry, I'm a little slow on the uptake...
steveo
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You will read faster than you are really going
Sit a little lower
Handle a little better
Zag
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my numbers are not corrected
i only go by what I see ....my tires are suppose to be 28.85 inches never did measure them
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my numbers are not corrected
i only go by what I see ....my tires are suppose to be 28.85 inches never did measure them
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One more point!
Vehicle designers are now going to smaller tires for improved mileage.
According to "experts" smaller tires accelerate easier using less energy. Smaller tires have lass contact patch on the road so less rolling resistance.
Apparently even at cruising speeds the rolling resistance and the acceleration deceleration make the smaller tires are more efficient.
Therefore better mileage for smaller tires.
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The only thing about contact patch is with Swampers, aired up to normal road pressure they have less contact area than 215 all terrains due to the interlocking center tread design...