2000 S430

I have read all the posts and still need help. I have new AMG wheels and tires that are wider in the back. The cruise now stops working at 66 mph. I have tried to press the ESP button and still get the same thing. Is there ANY way to get this to work shor of changing the tires to the same size? I should have read about this prior to spending 3k on wheels and tires. All your help will be appreciated.

Jack

 

I don't hear much talk about it in the M-B forums, but I know that GM and Ford ECUs store tire sizes. One reason is to calibrate the speedometer, but more importantly as a variable to compute the the trans shift points and stability control and all that stuff. Anyway, why don't you try calling one of the M-B ECU reprogrammers and ask them if they can do some custom programming to help you?

 

We had quite long post about matching rpm (rounds per mile) of the tires on this forum.
Lugnut couldn't understand why it is important to match rpm different tires on the car, but hopefully you will?
https://mercedesforum.com/m_27549/mp...m/tm.htm#27722

 

Wider should not be a problem. Larger in diameter may be. What did you go from too?

Bazzle

 

Everybody already knows this, but Kajtek1 is incapable of undertsanding what happens when tires are different sizes. He thinks all tires are the same size when rotating based on some obscure design parameter called a "round per mile" which I've never seen included in a tire's specs for retail. I believe this is a design variable and not a real-life variable.

He completely ignored you when you said your tires are different sizes because he wants so desparately to validate his corny "rpm" theory. If your tires are different sizes, they'll remain different sizes when they are rotating. Hopefully, you can undertsand this very simple concept and progress beyond the petty and irrelevant obstructions presented by Kajtek1. Wider tires will bulge a little more than narrower tires when they rotate at given speeds. This results in the wider tire becoming even larger in diameter than the narrower tire when they are both at rest.

For some unexplicably odd reason, Kajtek1 will misdirect you by insisting on discussions of his "rpm" theories. Listen to him if you want to waste your time.

 

Thanks for everyone's input. I guess with all that said, The only fix is to get the tires all matched up?

 

Maybe some programming would correct it?