If I move to 20" wheels all around my C6 will I need to adjust the speedo at all? If so how is this done? I've heard I just need to move to a side wall of 30 in the front and 25 in the rear?

Any advice would be helpful and appreciated.

Mike

I believe you will need to, a tuner should be able to do that for you.

I believe you will need to, a tuner should be able to do that for you.

:iagree: The speedo will need to be adjusted with the bigger wheels and tires. I think the Diablo Preditor will do the trick?

I'm looking at new wheels for my '07, wouldn't going to a larger wheel take away from actual HP on the ground because of the increased weight of the wheels? I think the bigger the wheel (with in reason) the better it looks on cars, it just fills the wheel well nicely.

GM has that recalibration formula is if they still use it for speedo adjustments for say snow tires or no longer tires available but say same tire but an inch off or less (for argument sake) is that extra (inch) times 360 is that speedo off now is to manually recalibrate is if someone has a FSM? It might be in the shop book for that recalibration value to reprogram the ECM to wheel rotation. Just a guess what I used to do in the early 90's is forgot most of it.

GM has that recalibration formula is if they still use it for speedo adjustments for say snow tires or no longer tires available but say same tire but an inch off or less (for argument sake) is that extra (inch) times 360 is that speedo off now is to manually recalibrate is if someone has a FSM? It might be in the shop book for that recalibration value to reprogram the ECM to wheel rotation. Just a guess what I used to do in the early 90's is forgot most of it.

Thanks for the tips and information :patriot:

Here's the stock speedo section for an 08 Z06 in HP Tuners (http://www.hptuners.com).
The gear ratio shows as 1.0 because the output shaft turns 1 revoltion to every tire revolution.
In other applications it shows up with the current gear ratio.
Stock gears on the manuals are 3.42 BTW.

http://i299.photobucket.com/albums/mm309/DynamicTuningSolutions/Speedo-08_Z06.jpg

I like the staggered look to much to go with the same size all the way around.:cheers:

I will be moving to 20's all the way around in couple weeks when the new wheels and tires arrive, Advance Dyno was telling me its a quick adjustment. Will post some photos when I get the car back. :cheers:

That is the max size of wheels that I would ever go with on a Vette. I remember seeing one with 22's all the way around!!:eek: Not good looking at all.:ack2:

Here's the stock speedo section for an 08 Z06 in HP Tuners (http://www.hptuners.com).
The gear ratio shows as 1.0 because the output shaft turns 1 revoltion to every tire revolution.
In other applications it shows up with the current gear ratio.
Stock gears on the manuals are 3.42 BTW.

http://i299.photobucket.com/albums/mm309/DynamicTuningSolutions/Speedo-08_Z06.jpg

Cool graph, just makes me wonder who sat around thinking of this!

I don't know why you would mess with perfection:willy_nilly:

I don't know why you would mess with perfection:willy_nilly:

Just looking to fill more of the wheel well. :thumbsup: