Odometer not reading accurately

98blacksr5

98blacksr5

New member
I just bought a 98 Toyota 4runner 2wd auto transmission with 120k miles and when we got home from getting the truck 100 miles away we noticed the the odometer was not reading right, it seams to be going real slow on the last number, so can this be from a faulty odometer or speedometer sensor, or can someone could have tampered with it? any input on this would be great, thank you.
 
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check your wheel size, if you have 16'' rims, u should have 265/70 tires, if you have 15'' rims i believe you should have 265/75 or 245/75 tires.

you said its "slow" so that means u probally have bigger tires than stock size.
 
98blacksr5 said:
They are 235/75/R15
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That's why it's reading off.

It's a minimal difference really but the tire size is supposed to be 225/75/15.

I had the original size the same on mine too, but now im at 265/70/17, which is a difference of a 28.3 inch tire to a 31.6.

My speedo/odo is pretty off lol.

Here are the differences:

Speedometer reading is 2.1% too slow.
When your speedometer reads 60, you're actually going 61.3mph.



Which is really not that big of a deal. Mine is ridiculously off.

My speedo is 11.7% off, speedometer reads 60, I'm actually going 67mph.
 
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Its better that way, then it appears the vehicle has less miles then it really has (better for resale), mine is the opposite, i am off i little bit, when the speedo reads 65 i am doin 62. Nothing major.
 
ChildrenOfBodom said:
That's why it's reading off.

It's a minimal difference really but the tire size is supposed to be 225/75/15.

I had the original size the same on mine too, but now im at 265/70/17, which is a difference of a 28.3 inch tire to a 31.6.

My speedo/odo is pretty off lol.

Here are the differences:

Speedometer reading is 2.1% too slow.
When your speedometer reads 60, you're actually going 61.3mph.


Which is really not that big of a deal. Mine is ridiculously off.

My speedo is 11.7% off, speedometer reads 60, I'm actually going 67mph.
Click to expand...

whoa..i thought the first 3 numbers were the "width" of the tires...and the middle 2 numbers were the "height"?????????????? i always thought 265/70 were wider than 245/70....but 265/70 were shorter than 265/75!
whats the deal with the 3 first numbers then?

b/c i bought a pair of 275/70/16 for my front tires...uh oh...
 
You are correct the first 3 numbers correlate the width ratio. That's why I'm confused as with the two tire sizes there really only is less than a .5" difference. The height of the tire is based on the next two numbers. For instance my tires are 255/85-16. The 85 dictates my 33.5 inch tire diameter not the first three numbers
 
rdgt4r said:
You are correct the first 3 numbers correlate the width ratio. That's why I'm confused as with the two tire sizes there really only is less than a .5" difference. The height of the tire is based on the next two numbers. For instance my tires are 255/85-16. The 85 dictates my 33.5 inch tire diameter not the first three numbers
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yea..so either childrenofbodom is wrong, or hes right and im missing something...however i remember reading somewhere that the second set of numbers is the ratio to the first set of numbers...so like 265/70 means 70% of the 265mm... but like 275/70 would be a taller b/c its 70% of 275....

grr someone clear things up? have i not been running stock tires all this time?! i thought the second set of numbers was what really made the difference in the height of the tires.
 
yep he was right, the 2nd set of numbers is the ratio to the first set..in which my case i have 275/70..which turns out to be 192.5 mm...whereas recommended size is 265/70 which is 185.5 mm ..so i really have a 7mm lift! WOOT!
 
brian2sun said:
How far off is your odo? You said you drove it back 100 miles, what did it read?
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Well when I got it this Thursday it read 120,84 and the drive home was about 100 plus miles and now it reads 121,02 not to mention the driving we have been doing around town, this is way of to me. I don't know if i should replace the odometer with a used cluster close to what i have or what? don't know where to start. I hope this thing doesn't have a ridiculous amount of miles then what I paid for.
 
bak3rme said:
yep he was right, the 2nd set of numbers is the ratio to the first set..in which my case i have 275/70..which turns out to be 192.5 mm...whereas recommended size is 265/70 which is 185.5 mm ..so i really have a 7mm lift! WOOT!
Click to expand...

Yup, exactly why 265/70/17 is a 31.6 inch tire while 285/70/17 is a 33 inch.

I heard somewhere that the second number is a percentage of the first number... so the height of those two differs as 70% of 285 is a larger number than 70% of 265.

So likewise 235/75 vs 225/75 would account for just a tad bit more height.

I hope this thing doesn't have a ridiculous amount of miles then what I paid for.
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Don't worry about your miles, if anything it's really not off by really much at all. It's such a small difference. Just imagine 11.7% off like mine, or some of the people with 35's and 33's.

If it really bugs you, you can look into Dakota Digitals speedometer correction box, which I will install soon. A member here, 240m3srt, has done this to account for his 35" tires.

And hey, like John said, looks like you have less miles!
 
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The first three numbers are the width of the tire in millimeters.
The second number is the aspect ratio...the relationship between the tire height and tire width. A 70 means the tire sidewall height from rim to tread is 70% of the tire width.
The R stands for radial construction.
The third number is the wheel (rim) diameter in inches.

This page explains the hieroglyhpics pretty well: Tire Tech Information - Tire Size Guide
 
Thanks childrenofbotom and all you other guy's for your all your info, now i'm not as worried. So if i wanted to put some 16'' wheels and a little bit bigger tires it will make it worse then it is? Thanks again guy's.

ADAM.
 
Im running 33's and im only off 5% I just do most of my speed gauging and distance calculations from my GPS anyways.
 
rdgt4r said:
Im running 33's and im only off 5% I just do most of my speed gauging and distance calculations from my GPS anyways.
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Just know when you read this, 98blacksr5, that some 4Runners came stock with 225/75/15 and some came with 265/70/16.

In our case, if we were to put 33's on our trucks, we would have a much larger difference than rdgt4r, since he had larger tires from the factory.

Technically, yes, your speedo will be worse if you go up in tire size. It's all in the diameter of the tire, doesn't matter the rim size. A popular change for most people with 4Runners are 265/75/16s or 265/70/17s. They're practically 32" inch tires and are the largest tire that will fit without lift. A change from your stock size to a tire like that would give you a pretty big difference in speedo readings. When I'm going 58 on my speedometer, I know I'm actually going 65, and there are ways to correct the speedometer afterwards.

Also, you could upgrade to the stock size for the Limited and some SR5 4Runners, 265/70/16, which would be about a 30.7 inch tire.

A great website to use in order to find out what tire sizes are best for you:

Just make sure that the first tire is 225/75/15 and then plug in your desired size.

http://www.miata.net/garage/tirecalc.html
 
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Try driving another known set distance. I assume you used google maps or mapquest to get the distance from where you bought it which sometimes can be way off.
 
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