Speedo and 33's

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Joined
Mar 1, 2010
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48
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136
Location
Albuquerque, NM
Should I expect that my speedometer is off with 33's. Either the rest of the world is driving slow as heck or my speedo is off?
 
on a fully stock Crusier, stock gearing but with 33"s say your speedo is saying 55mph how fast are you really going? how far off is it usually?
 
on a fully stock Crusier, stock gearing but with 33"s say your speedo is saying 55mph how fast are you really going? how far off is it usually?

The speedo should be right on with the stock size tires but with 33's and stock gears this is right.

55 mph x 1.13 = 62 mph or 12.7% off
 
haha yeah soon as i posted i saw your math. roger that.
 
I put 10.5x33 on and when my speedo is at 60 the gps reads 67 or 68. Did not know the 1.13 multiplier trick is great. Does it work for the odometer also?
 
54.8 mph is 61.8 mph. Thats at 2350rpm.

So thats exactly 7 mph off at that speed.

So to find your speed with 33's multiply speedo reading by 1.13 which is rounded from 1.127 the difference between the height in the "33" (actually 32.7) inch tire and the stock 29 inch.

Norcal's Chart is awesome!


EDIT: Some people post faster than me! sorry haha
 
I put 10.5x33 on and when my speedo is at 60 the gps reads 67 or 68. Did not know the 1.13 multiplier trick is great. Does it work for the odometer also?

Works for odometer too. Speed and mileage is from the same cable on transfercase.

For Gas Mileage:

Take your miles on trip meter, multiply by 1.13, divide by the gallons and there is your miles per gallon!

If only that number was higher more often :crybaby:
 
Does it work for the odometer also?

yes, the odometer is off by the same ratio.

The 1.13 is for just stock gearing and 33's. When you change the gearing or tire size or both then it changes the ratio. The excel file I made should be accurate but let me know if you find a error and I will fix it.
 
I seem to remember discussion a while back about different ratio speedo drive gears available from Toyota that could correct an off speedo for situations like this. Anyone remember P/Ns?
 
Now throw 4.88's into the eqaution and my speedo reads faster than I am going. Speedo reads 56, GPS says 50... Now I just read the GPS for speed and forget the fact the odometer of my Canadian rig reads in kilometers.

Tony
 
If you have not changed your gears, you are way off. Even with 33s and 4.10s you will read a bit low.
mike you got it mixed up lol, my cruier with the 4:11's and 33's will sett the spedo to stalk ratio along with this: ->
4:56= 35''s
4:88= 37''s
and on and on I was thinking about this the other day and figured it out pretty high up
 
Hijack: I am running 3.73 gears with 33" tires, along with a 5.3L Vortec & H55. How will going to 4.11 gears affect my gas mileage?
 
Hijack: I am running 3.73 gears with 33" tires, along with a 5.3L Vortec & H55. How will going to 4.11 gears affect my gas mileage?

You will run higher rpm's going down the interstate. So if it's drivable with that engine combo I say leave it. And theoretically lower rpm would grant higher gas mileage. Theoretically.

I like the "rubber overdrive" I get from my 33 inch tires because I have yet to regear either. Don't think I really want to :D
 

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