Hi all. First time posting here. I drive a 2002 C240 Classic (Canadian base model) with the 5 speed auto.

I recently upgraded to 225/45 17 inch tires and rims from my stock size of 205/55 16 inch. I have noticed that my fuel efficiency has decreased slightly (according to my trip computer), especially on the highway, usually cruising anywhere between 100-120km/h. I have the tire pressures set to the factory recomended levels (32psi in the rear, 28 in the front). This is what the dealer recommended as well with the new tires/rims. The tires I have are Falken Ziex ZE512.

So my first question is this: has anyone noticed a change in their fuel efficiency when changing to wider tires and larger rims? My brother said that was possible given potentially higher rolling resistance of these wider performance tires compared to the stock Continentals.

My second question relates to anyone on this board who has experience with the Kleeman Super charger upgrade for the C240. Has anyone tried this? Any problems with future servicing or maintenance performed by the dealer? I posted this particular question on other forums, but I have heard close to nothing about it, other than the fact that the Mercedes warranty will almost certainly be voided.

 

From my experience, 32/28 is a bit on a low side. I use 36/32, and if feels perfect. Better control, and definitely better rim protection, especially now - until they repair all these fresh potholes.

 

Your new wheels are bigger and heavier, which means the car will need a bit more power to run them. So it is normal for the fuel efficiency to go down a bit.

I dont think a lot of people have installed the Kleemann supercharger upgrade on a C240, because with the price that you're paying, you can buy a C320 (or almost a 32).

 

I changed mine from stock to 225 40/18 and the psi is 44. Check from the tire side wall, it should says ##psi.

 

That is not the psi that you're supposed to inflate your tires to automatically. Do it and you'll wear out your center, decrease tire life and handling.

Follow the MB recommendations and adjust from there based on you load and driving habits. Check on the tire forum. I believe Luke from the tirerack made a statement regarding this.

 

Tuat's more likely the max pressure the tire can handle. 44 PSI certainly it too much for a street use.

 

i have 30 front 32 rear on stock 16s...

i'm already finding that the car understeers a lot more than at 28 front.

 

from the Mercedes-Benz website:

Z-rated tires are optimized for performance driving and may provide reduced ride comfort, increased tire noise, substantially increased treadwear and greater susceptibility to damage compared with H-rated tires.

Would this also apply to fuel consumption?