I put 33's on and now I think my odometer is off. Does anyone have any insight on this?

 

Yes when you put the bigger tires it changed how fast you are going. I am guessing you will be going between 3-7 mph faters then what the speedo shows. I'm sure someone will be along shortly to give you more information on this.

Charles

 

Its a ratio and proportion problem. Back to MATH, yikes! Lets say the stock tire was 30 inch, then 60 is to 30 as 66 is to 33. Your speedometer shows 60 mph but you are actually driving at 66 mph. So you would have to drive at 54 to be actually driving the speed limit of 60. OR look at this way 60/30 = 66/33. Also the speed you are driving affects the amount of change. At speed limit 45 it would be 45/30 = X/33 to find X = (33 x 45) / 30, X = 49.5 so to drive 45 you would subtract 4.5 (the amount over the desired speed)from 45 and drive at 40.5 mph to be within the speed limit.

 

Here's a couple of links that will help you with your calculations and more.

Regards, Glenn

http://www.drivetraindepot.com/gear_calculator.asp

http://www.1010tires.com/TireSizeCal...?action=submit

 

just my 2 cents, but if you put bigger tires on (larger diameter) the revs per mile would go down, which would mean you'd cover more miles with less revs. not sure what the odometer reads miles off of? but i'm pretty sure you're odometer would not be adding them up correctly? you would have gone more miles than the odometer registered, but thats a good thing right? how much it would be off, i'm not sure.

 

I have 33's on and am roughly 6% off on the speedo when compared to other trucks.

 

What about brakes? Do I need new discs or anything? am I running a potential safety hazard?

 

No safety hazard that I can think of other than to watch your speed to avoid speeding tickets which could be a hazard to your wallet and higher insurance rates. The benefits are greater speed with less RPM's which means better feul mileage.

 

i went from the stock tires to a 305/70/17 which roughly calculates out to about 33.8 inches tall. according to my GPS, my speedo is now off 10%. speedo says 30, i am doing 33, at 60 i am doing 66 and at 70 i am doing 77. hope this helps!

 

Anyone know of a programmer or anything that can adjust the spedometer without changing any power settings?

My superchips flashpaq adjusts the spedo, but I can't use it in conjunction with my Edge Juice/Attitude. I tried....they don't work together.

I think the Edge performs better, but it doesn't alter the spedo.

Any thoughts?

-Nate