LUVTruck.com

where can i go to find out how much my tires through off my speedo? matt

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1980 4x4 header stock motor lifted 4 1/2 in. in the rear and 3 1/2 in the front

There's 2 ratio calculators in the information section of this site. You can figure out the RPM's, tire size, MPH, or gear ratio. Just enter the info thats needed to figure out what you want to know.

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Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

i tried them both and neither one would tll me how fas i wa goin if my speedo said 60. and i don't know all the info so if somebody can do it for me that would know the info. i am running 30 in tires with the stock motor and tranny.n e help would be appreiciated. oh ya i had a buddy tail me and he said when my speedo said 65 i was actually goin 75 is this possible?

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1980 4x4 header stock motor lifted 4 1/2 in. in the rear and 3 1/2 in the front

Do you know how tall the other tires were? If so, You can figure out the original setup to get the engine RPM's @ 60 MPH. Once you get the RPM calculated, Calculate that RPM with the new tire size and 4.10 ratio. This will give you the new speed.
First figure:

Old tire size = 27?"
Speedometer reading = 60 MPH
Gear ratio = 4.10
To Get / Engine RPM = !@#$

Then you can figure:

New tire size = 30"
Gear ratio = 4.10
Engine RPM = !@#$
To Get / Speedometer reading = XX MPH

It's not a perfect science figure but it's in the ballpark.

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Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

yes, that speed is possible, i had 31 inch tires on my 79 ford, and it's speed was 10 mph off. 75 when my speedo said 65.