birdman-c

Hi guys,

Installed 245/40/18 in the front and 275/35/18 in the back on my w211. I noticed that when I am travelling 60KM/H the car is actually travelling 58KM/H etc. The car is always reporting 2KM faster than I am actually going, verified with my handheld GPS.

Is it possible to recalibrate this show my car shows the correct speed?

Thanks!

amdeutsch

You will find that different tires have different diameters. Not much but a mm or 2 can easily be seen. Now take air pressure into account which once again can and will affect that parameter. Last but not least you will have to deal with the different thread depth which can vary from 6.5 mm to 8 mm depending on tire, brand, etc. Wear that off and once again you'll be faced with the same dilemma.

jameson75

Well that because you've changed the "rolling diameter" of your wheel/tire setup. You don't mention what came stock on your mercedes. My E500 came with the 245/45/17 wheel/tire setup. This has a rolling diameter of 25.68"

Looking at your setup, the front is at a 25.72" and rear is at 25.58". When upgrading wheels and tires, you should always try to maintain the same or close as possible rolling diameter, so to not drastically effect things like speedometer accuracy, transmission operation, etc.

birdman-c

I am using the E55 wheel setup - which is what tirerack recommended. 245/40/18 in the front and 235/35/18 in the back. The stock setup is 225/55/16 all the way around I beleive (stock e320 setup).

I assumed all the e-class speedo's would be calibrated the same. How can I recalibrate to the E55 setup?

LeslieRushforth

I have recently installed a GPS speed camera detector (locator)on FIXED and Mobile speed traps her in the U.K. it is called a SNOOPER.
It as a data base of the cameras location which can be upgraded by downloading the latest information where the cameras are located.

Here in the U.K. the police go crazy......there are so many speed cameras and mobile so called (safety camera vans) around it,s untrue.....3 miles M.P.H over you get a ticket.

GETTING BACK TO SPEED READING ON MY E320 CDI (W211).
I notice that the GPS SNOOPER shows 2 to 3 M.P.H. MORE than the actual speed thats on the cars own speedometer.THIS IS ACCROSS ALL THE RANGE FROM 20 TO 100 M.P.H.......I am using stock tyres.

CONCLUSION
Most all car manufactures these days set the speedometers to read 2 to 3 M.P.H. MORE THAN THE ACTUAL SPEED THAT THE CAR IS TRAVELING.
This is to HELP the driver keep within the speed limits.

04 build.. 24.000 miles .....Just 2 rear shockers replaced.

Les...Chestefield....U.K.

steph280

I've been running the E55 wheels for a while and that few mph difference doesn't really bother me.

vraa

Even with stock wheels it'll still be off by a bit. It's just a caution. Better be be reporting yourself to go faster then to be slower so you don't speed.

birdman-c

Well, it adds extra KM's to your odo - that is what bothers me...

vraa

It's a percent or so.

If I remember right, it'll be something like 1mph + @ 62mph or so.

That's miniscule.

If you travel 200,000 miles (the average life we keep our cars) that's an additional !3300 miles. Not a big deal.

If you're going to sell the car at 50,000 miles, that's an additional 810 miles. Personally, I still think it's not a big deal.