1997 toyota land cruiser speedometer 5 miles an hour slower then what gauge says.

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Kevin LeClaire

Kevin LeClaire

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Hey guys, I did a search for this issue and nothing is coming up and I'm really not a fan of the search engine here om MUD because it just does not seem to work for me. As the title says I will be going 55 according to the speedometer but I am only going 50. I checked it with google maps and there is a flashing speed sign down the road and every time I go by it will be 5 miles slower then what I am going. I have the regular small tires on it and in the summer I put toyo atII extremes on and there bigger then what I am running now. Any idea what is going on, thanks.
 
Road Apple

Road Apple

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When you install larger tires with stock differential gears, your speedometer will be off.

“Up-sizing, or installing a taller tire, will lead to a speedometer reading that is slower than your actual speed. This is because a taller tire will have a larger overall circumference, causing it to need to travel more distance per revolution than the original equipment tire.”

You can correct it by adding a yellow box or installing lower gears in the differentials. Here is a gear calculator and the appropriate tire and gear combinations for stock gearing.

31” tires - 4:10 gears
35” tires - 4.56 gears
37” tires - 4.88 gears
39” tires - 5.29 gears


 
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Kevin LeClaire

Kevin LeClaire

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When you install larger tires with stock differential gears, your speedometer will be off.

“Up-sizing, or installing a taller tire, will lead to a speedometer reading that is slower than your actual speed. This is because a taller tire will have a larger overall circumference, causing it to need to travel more distance per revolution than the original equipment tire.”

You can correct it by adding a yellow box or installing lower gears in the differentials. Here is a gear calculator and the appropriate tire and gear combinations for stock gearing.

31” tires - 4:10 gears
35” tires - 4.56 gears
37” tires - 4.88 gears
39” tires - 5.29 gears


Great thanks I will check them out.
 
Kevin LeClaire

Kevin LeClaire

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When you install larger tires with stock differential gears, your speedometer will be off.

“Up-sizing, or installing a taller tire, will lead to a speedometer reading that is slower than your actual speed. This is because a taller tire will have a larger overall circumference, causing it to need to travel more distance per revolution than the original equipment tire.”

You can correct it by adding a yellow box or installing lower gears in the differentials. Here is a gear calculator and the appropriate tire and gear combinations for stock gearing.

31” tires - 4:10 gears
35” tires - 4.56 gears
37” tires - 4.88 gears
39” tires - 5.29 gears


I have 305 70 R16 which is around 32.8 tire
 
C

clx16

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I think this might be what you need 3340369225 for that tire size.

 
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WCBlueSky

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SpenserAK

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Makes sense for the 305s, but if this is also happening with your stock tire size, not sure why.

Mine came with 315s (34.6”) and no correction, and was about like yours - said 50 but was going ~56. I used the yellr box and now it’s spot on.

As for the search function, I tend to use google - it can be hard to find what you’re looking for when searching here, with so many threads. Google what you’re looking for and add “ih8mud” - usually works great for me.
 
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ChaseTruck

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... I will be going 55 according to the speedometer but I am only going 50....
That's not 'rubber overdrive', as alluded to in several previous posts. Sounds like someone 'secretly' geared down the truck... or the 'stock' tires are really, really small. Like, e.g. BFGs
 
mjosoba

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Kevin LeClaire

Kevin LeClaire

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I think I’m going to go the yellow box route, should be pretty easy to install and once it’s in it will be easy to make an adjustment in the future with out getting your hands greasy. Thanks for all your help.
 
Ozark80

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I've been noticing this same exact thing. Didn't change at all when I went from 31s to 33s. In fact my old Tacoma's speedo was 5 mph slow also.

I'm thinking it's just another old Toyota quirk like the gas gauge that goes up whenever you drive up a hill, or the constantly wandering oil gauge..
 

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