Any reason I cant use 45 profile on 18s

pits200 · 07-13-2015, 09:35 PM

I'm sick of the potholes and bent rims. Besides the Speedo being off, is there any reason I can't use 235 45 18 tires instead? Our speedos are already over by about 3% so technically this would be counter that slightly and give me more rubber to protect.

AceOnShake · 07-13-2015, 09:39 PM

I used that setup before it seemed to correct the speedo and checked with GPS from my phone. It makes it look more tucked and more protection from pot holes!

dauble2k5 · 07-13-2015, 09:48 PM

I'd be interested in knowing this info too. Gotta love the midwest.

parksjm7 · 07-13-2015, 09:48 PM

Just be mindful that usually, a wider diameter to rotate results in lower MPG and lower torque from the engine measured at the wheels - I read it's about 4% of such torque is reduced per inch you go up (if you go from 40 to 45, it's roughly an inch) I've learnt it the hard way. If I could do it over again, I'd stick with the same number of profile.

mk1bmw · 07-13-2015, 10:05 PM

I run 225/45/18 in MN, they ride way better than the factory 225/45/17 run flats and the speedo is dead on.

07-13-2015, 09:35 PM	#1
pits200 Colonel 547 Rep 2,590 Posts Drives: 09 335i X-Drive Black Sapphire Join Date: Mar 2010 Location: Pittsburgh iTrader: (1)	Any reason I cant use 45 profile on 18s I'm sick of the potholes and bent rims. Besides the Speedo being off, is there any reason I can't use 235 45 18 tires instead? Our speedos are already over by about 3% so technically this would be counter that slightly and give me more rubber to protect.
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07-13-2015, 09:39 PM	#2
AceOnShake Lieutenant 39 Rep 592 Posts Drives: E90 Join Date: May 2007 Location: Windy City iTrader: (0)	I used that setup before it seemed to correct the speedo and checked with GPS from my phone. It makes it look more tucked and more protection from pot holes!
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07-13-2015, 09:48 PM	#3
dauble2k5 Private First Class 57 Rep 180 Posts Drives: 2011 VR E92 335i, 6MT Join Date: Jan 2015 Location: Earth iTrader: (0)	I'd be interested in knowing this info too. Gotta love the midwest.
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07-13-2015, 09:48 PM	#4
parksjm7 Second Lieutenant 81 Rep 228 Posts Drives: E92 07 335i Join Date: May 2012 Location: Edison, NJ iTrader: (0) Garage List 2007 BMW 335i [0.00] 2002 Honda [0.00]	Just be mindful that usually, a wider diameter to rotate results in lower MPG and lower torque from the engine measured at the wheels - I read it's about 4% of such torque is reduced per inch you go up (if you go from 40 to 45, it's roughly an inch) I've learnt it the hard way. If I could do it over again, I'd stick with the same number of profile.
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07-13-2015, 10:05 PM	#5
mk1bmw Registered 0 Rep 3 Posts Drives: 2008 BMW 335xi Join Date: Jun 2015 Location: United States iTrader: (0)	I run 225/45/18 in MN, they ride way better than the factory 225/45/17 run flats and the speedo is dead on.
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