How much is my Speedometer going to be off?

[SuprSpdDB7]

I currently have 16" stock rims. I have purchased 17" rims to replace them. How much will my speedometer be off by doing this?

Eventually i am going to take it to the dealership to get the speedo recalibrated because i am also getting 3.42gears soon. But i need to know in the mean time... [img]graemlins/fluffy.gif[/img]

[John_D.]

<blockquote>quote:</font><hr>Originally posted by SuprSpdDB7:
I currently have 16" stock rims. I have purchased 17" rims to replace them. How much will my speedometer be off by doing this? <hr></blockquote>

Depends on the tire size...

A search, on a calculator for tire sizes, should turn up a couple of links. You can put in the old and new sizes, and it will tell you differences in rpms, speedometer, and effective gear ratio. If a search doesn't get you some links, let me know, and I will find a link or two for you.

[V6Bob]

Knowing how to do the calculation may help.

tire diameter in mm = (tire size in inches X 25.4) + (tire section in mm X section height in % X 2).

Example 215/60-16 (stock size):

16X25.4 + 215X60%X2 = 406.4 + 258 = 664.4mm

Your speedo will be off by the amount the tire diameter is off from stock. Tire sizes do vary a little from this ideal, but it will be close.

[DominusEtDeusNatus]

It's not the rim, it's the total tire height like they said above. Sidewall will be smaller with bigger rim size. Most of the time it won't be off by much.