Giedreb

Just took off OEM 18s and put on 19s and the shifts are all coming too soon and off kilter. Is an ECU reset or something similar needed to get the new driveline ratio adjusted for?

CarHopper

No? The shifts should have nothing to do with your wheel size.

Ingenieur

What size tires?

12C63AMG

Just joined the forums after picking up a 2012 C63 Perf Pkge.

Major spinning with 18in 255s in the rear. I guess the 481HP will do that ... lol

Could someone please assist me in confirming whether 19 x 9.5 rims with a +45 offset using 265/30 tires rub / fit ?
The manual says an offset of +54 is required for the rears, but I can't find that offset in non-oem rims anywhere.

Thanks everyone...

Giedreb

Something is definitely off, all the gears cycle in at 5-10 mph lower speeds than before. 7th is in at 48-50 mph for example. New tires are 245/35 and 275/30

Ingenieur

The rears are ~2% larger
That shouldn't affect the ecu but who knows

What did it shift at before?
Into 7th at 50mph ?
What tranny mode?

CarHopper

Those are the right sizes. It must be something else going on or it is how it is supposed to be and you're mind is playing games with you because you have on new wheels.

Giedreb

It would shift into 7th above 55-60 in all modes previously. I'm going to reset the ECU overnight and see what happens. Typically wheel size changes require ECU updates to correct the speedo since the revolutions per mile are different. Not sure if this affects shifting if no one else ever seen this issue when upgrading wheel size,

Ingenieur

The difference is minor
What was 50 mph is now 51 mph for the same engine speed
There must be at least that tolerance in the system(s)
Tire wear from 10/32 to 2/32 is the same of change

N979Q

Pics please. I'm thinking about going to 19s just to make cleaning the wheels easier.

Andy

Giedreb

A few pics.