anyone good at math?
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Pikeman
New member
Well you can google tire calculator and some of them will tell you the percentage difference. Then multiply by that percent and wil give you miles traveled.
Tire Size Calculator - tire & wheel plus sizing
Tire Size Calculator - tire & wheel plus sizing
I agree. Shoot.....I'm somewhat of a math nerd and I got all excited for a second!
Edit: I got bored and looked it up for you. (I just put those exact wheel tire combo on my brother's 1st gen Taco. It looks good!)
7.59% difference. So....60mph in real life is gonna read 55-56mph on the speedo.
Take mile traveled and multiply by 107.59
Last edited:
J-money$$$
New member
multiply by 1.0759
theizzardking
New member
all sorts of calc's here-
4Lo.com :: Speedometer Check Calculator
and a good one for speedo here
Speedometer Calibration / Tire Size Change Calculator
Martinjmpr
New member
The problem with calculating using nominal tire size is that nominal tire sizes are, well, nominal. They can be bigger or smaller than their nominal sizes enough to make a difference in calculation (IOW, not all 265/75/16 tires are exactly 31.64" tall.)
So the best way to judge MPG is to find a known, measured distance and compare the known distance to what the odometer shows. The easy way to do this is to just use a GPS. Most GPS units have a trip meter. Set the trip meter on the GPS to 0 and set the trip meter on the 4runner to 0. Drive a certain distance, say 10 miles, and then compare the two distances, that will show you what your correction factor is.
Using this method on a long trip (about 250 miles) I calculated my speedo/odo error at 3.2% (using 265/75/16's vs the stock 265/70/16s.) So, when I fill the tank, I take the miles shown on the trip meter (which I reset each time I fill the tank) and multiply by 1.032. That give me my actual miles driven, then I divide that by the amount of gas I put in and voila - correct MPG!
So the best way to judge MPG is to find a known, measured distance and compare the known distance to what the odometer shows. The easy way to do this is to just use a GPS. Most GPS units have a trip meter. Set the trip meter on the GPS to 0 and set the trip meter on the 4runner to 0. Drive a certain distance, say 10 miles, and then compare the two distances, that will show you what your correction factor is.
Using this method on a long trip (about 250 miles) I calculated my speedo/odo error at 3.2% (using 265/75/16's vs the stock 265/70/16s.) So, when I fill the tank, I take the miles shown on the trip meter (which I reset each time I fill the tank) and multiply by 1.032. That give me my actual miles driven, then I divide that by the amount of gas I put in and voila - correct MPG!
greenmonkey
New member
Ok so I thought I did this right but my numbers don't seem right. So I had 265/65/17 and now have 285/70/17. Thats a diameter difference of 6.55% and a speedometer difference of 7.012%. From what was said if I go 200 miles and Multiply that by 7.012% I should get my actual miles traveled? My number is way too big. I just think I don't under stand what to do. This is something I really want to figure out because my milage is off and my fuel milage is off. Please help me.
J-money$$$
New member
take mileage driven multiply by 0.07012 That will give you the number that you then add to the mileage reported on the odometer.
REMEMBER 7.012% = 0.07012
REMEMBER 7.012% = 0.07012
TheDurk
Elite Member
Easier to just multiply the miles by 1.07012.
200 ODO miles x 1.07012 = 214.02 actual miles.
LINY4Runner
New member
I was shown this method:
new tire size/old tire size=(difference)x speedo or odo= actual
here's [roughly] how yours would work out:
31/27= (1.15)x 55mph= 63.25mph
60mph = 69mph
65mph = 74.75mph
70mph = 80.5mph
watch your speed!
new tire size/old tire size=(difference)x speedo or odo= actual
here's [roughly] how yours would work out:
31/27= (1.15)x 55mph= 63.25mph
60mph = 69mph
65mph = 74.75mph
70mph = 80.5mph
watch your speed!
greenmonkey
New member
Ok so I did some math with the new num.
246x1.07012=263.24
So I did this three times with different numbers and averaged them to get 14.69 mpg. My average in my 4r says I'm getting 16.5. The problem is that the rig now how much fuel I'm going through and thinks I'm going less miles than I'm really going, so why is it saying I'm getting better milage than my numbers. If I'm actually going further than it thinks I am wouldn't my average go up not down? Thanks for all the input.
246x1.07012=263.24
So I did this three times with different numbers and averaged them to get 14.69 mpg. My average in my 4r says I'm getting 16.5. The problem is that the rig now how much fuel I'm going through and thinks I'm going less miles than I'm really going, so why is it saying I'm getting better milage than my numbers. If I'm actually going further than it thinks I am wouldn't my average go up not down? Thanks for all the input.
