[crinwa]

If i jack up my sierra and put 31 by 10s on it will i have to change my gearing ratio? and also my speedo?

[89_tintop]

you will have to change your gearing ratio for sure..

what kind of terrain you are running will then help with the choice of how you go about the change

i have 6.5 transfer gears and am absolutely rapt with them... low range is very very low. but high range is pretty much spot on with 31s.

[Ben_Sierra]

If you want it to drive anything remotely well then yes, you will need gears.

4.9s as a minimum though even 6.5s would be very acceptable on road with 31s...

And you will need to do something with the speedo if you want it to be accurate. (I just take an educated guess at my actual speed)

[crinwa]

damn
how much does it cost usually to change the ratio and how the hell do you do it?

[89_tintop]

gears are around 700 i think plus installation.

i dont know how to sought out the speedo though..like ben_sierra said i just guess.. with the 31s and 6.5... 100kph is about 80kph on the speedo.

i got an app on my iphone that shows me how fast i am going, how far i travelled and to what elevation

[Ben_Sierra]

With the speed just work out the % difference between the circumference of the stock tyres and new ones. Once you've got a rough % its very easy to estimate your speed.

[Red89]

crinwa wrote:

If i jack up my sierra and put 31 by 10s on it will i have to change my gearing ratio? and also my speedo?

You dont have to do it straight away the car will still drive fine without it, but it is advisable to do it at some stage as it makes life alot easier for both you and the car.

[joeblow]

while your at it order heavy duty transfer mounts etc....etc.....etc.........

[SuziBlu]

joeblow wrote:

while your at it order heavy duty transfer mounts etc....etc.....etc.........

Where do you get these Joe.