Tire diameter effect on DTC/DSC

Vetracr · 02-17-2018, 03:23 PM

I am currently running 235/40R18 tires up front (820 revs/mile)and 265/35R18 tires at the rear (823 revs/mile) on my Z4. I have had no problems with any DTC/DSC warning lights because the tires are so evenly matched. I want to upgrade to 245/35R18's up front (841 revs/mile) and 275/35R18's at the rear (815 revs/mile). I'm concerned about the DTC/DSC circuits activating the trouble lights because of the difference in front to rear wheel speeds. Has any one run this combination, 0.8" difference in tire diameter? Does anyone know how much difference you can run on a BMW without triggering a DTC/DSC fault?

paris1 · 02-18-2018, 12:21 AM

Anything more than a 3mm differential front or rear will make those functions hypersensitive in turns. When I put new tires on the rear without changing the fronts I ended up with a 4mm differential which made the DSC kick in too easily on freeway off ramps in the rain. Problem went away as the rears began to wear.

02-17-2018, 03:23 PM	#1
Vetracr Private First Class 30 Rep 193 Posts Drives: 2010 BMW Z4 3.0 Join Date: Jun 2016 Location: Palm Beach, FL iTrader: (0)	Tire diameter effect on DTC/DSC I am currently running 235/40R18 tires up front (820 revs/mile)and 265/35R18 tires at the rear (823 revs/mile) on my Z4. I have had no problems with any DTC/DSC warning lights because the tires are so evenly matched. I want to upgrade to 245/35R18's up front (841 revs/mile) and 275/35R18's at the rear (815 revs/mile). I'm concerned about the DTC/DSC circuits activating the trouble lights because of the difference in front to rear wheel speeds. Has any one run this combination, 0.8" difference in tire diameter? Does anyone know how much difference you can run on a BMW without triggering a DTC/DSC fault?
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02-18-2018, 12:21 AM	#2
paris1 Captain 90 Rep 745 Posts Drives: 2013 35i Space Grey over Coral Join Date: Oct 2014 Location: Northern Calif. iTrader: (0)	Anything more than a 3mm differential front or rear will make those functions hypersensitive in turns. When I put new tires on the rear without changing the fronts I ended up with a 4mm differential which made the DSC kick in too easily on freeway off ramps in the rain. Problem went away as the rears began to wear.
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