19" wheels = no cruise control?
 

I put 19" wheels on my w210 e430 and now my cruise no longer works over the speed of 75mph. Is there a fix for this(other than taking of the wheels)?

That means that the rear tires are SLIGHTLY smaller in circumference than the front ones!

The traction system doesn't like that!

curiousity prompts me to ask: why does it have to be the rear being smaller
than the front? could it ever be vice versa? also, how much differential must
there be between front/rear before the traction control (cruise control, et al)
begins to balk?

On cars with ESP and some with ASR, only a 3/8" difference can cause issues.

Since the cars are REAR wheel drive, the traction system is always looking for slippage of those rear wheels.

So if they are going faster that the fronts, it is designed to intervene.

great info - thanks, doc ! :thumbup:

I've checked different brands of tires they all have different outside diameters.Double check yourself O.D.

well, I had hoped to be able to posted a follow up of my success but it wasn't to be.

The cruise control regularly shuts off at 70 mph

the rear tire's circumference is 79.5". the front tire's circumference is 78.5"

which means the rear tire is *larger* than the front by by 1.25%.

next step will be to swap out the front tires with ones providing a 0% differential
and test the cruise control again.

good advice, especially if you're inclined to running with staggered rims.
my favorite tire interchange engine is this one, and for the 235-40-18
it shows the circumference to be 79.5 which is what I really need.

just to be thorough, I asked the vendor to measure the tire I was
contemplating purchasing (235-40-18) and he came back with 78.5"

there is 'theoretical' and there is real life. guess there is no ISO standard