speedo adjusting?

[retardedspleen]

so, i just went from 31-10.5 to 33-12.5 I knew my speedo would be off, but im not exactly sure how off..when the speedo says 70mph...it feels a little more like 83, 85mph... How would i go about adjusting this so its a little more accurate? is there a way I can do it myself?

[KToy]

u have to buy a speedo gear and it sits in the tcase to adjust for tires. with that small of tire upgrade i would assume at 70 ur going more like 73-75. get clocked or have someone drive next to ya and talk on a cell and let them tell u how fast u are going.

[AW1090]

I think there is a calculater that allows you to put in the gears and tire size......http://www.yotatech.com/~corey/portal/portal.htm#.....check there I think there is a link that will show you accel or ground clearance

[toy4x4]

there is no way that that small of a change in tire size is going to make a 15 mph offset in you're speedo. i would guess 2 or 3 mph. i wouldn't worry about it, it's not a big deal.

[tonkatoy]

hell if you have a handheld GPS then you could figure out the speed then you will be in that range, just remembering how many mph your GPS said what you were doing. i've done this to vehicles that you thought would be accurate but they were way off. Nick and also just got done replacing a friends Bronco tranny (nice ford P.O.S) :p:

[Silverbullet555]

I did the GPS method to determine the difference. With the current tires (275/60/15 I think) at 65 on the speedo I am actually doing about 71 according to the GPS.