E46Fanatics - View Single Post - 255/40/18 Front 255/35/18 Rear on ZHP Wheels

Dave1027 · 01-15-2013, 06:12 PM

It's because if you go 40 all around and go wider in back then the back 40s will be taller than the fronts and would roll at a different rate making the DSC throw an error. It's because the 40 number is not the height measurement but the ratio. This is why the 225/40/18 is the same height as the 255/35/18.

Look at this converter http://www.discounttire.com/dtcs/infoTireMath.dos

01-15-2013, 06:12 PM	#36
Dave1027 Registered User Join Date: Jan 2013 Location: California Posts: 387 My Ride: 2006 330ci ZHP View My Garage	It's because if you go 40 all around and go wider in back then the back 40s will be taller than the fronts and would roll at a different rate making the DSC throw an error. It's because the 40 number is not the height measurement but the ratio. This is why the 225/40/18 is the same height as the 255/35/18. Look at this converter http://www.discounttire.com/dtcs/infoTireMath.dos