Changing tire sizes / speedometer

sblument · 03-22-2006, 10:50 PM

Question: When you order your E90 is the speedometer calibrated to your tire diameter? For example between the base 325 with its 16" wheels and the sport pkg 330 with it's 18"...is the speedometer calibrated differently? Can this be done by the dealer/maintenance shop when they change your tires? Some people on this forum have 18" summer tires and 17" winter tires...do the mechanics reset or calibrate the speedo?

Boilerplate: I know similar topics have been covered before, but I searched "speedometer" and no one had previously answered the question.

ctgazer · 03-22-2006, 11:06 PM

i believe that you dont have to recalibrate your speedo cause as your rim gets BIGGER, your tire thickness gets SMALLER..thus the saying, ridin on rubber bands..so when you up the size of your RIM, your profile of the tire should go smaller to keep the original diameter of the wheel and tire intact

karbosshack · 03-23-2006, 12:11 AM

I'm sure mines off....goin from 16-20 will change the diameter....

ctgazer · 03-23-2006, 07:00 AM

haha, michael...i believe all of ours will be if we run 20's...but u gotta love the look

but you should always try and stick to the original diameter of the wheel and tire

JKing3 · 03-23-2006, 01:31 PM

I''d love to know this too. I'm wondering if the antilock system used in conjuction with the tire pressue monitor is what provides the speedometer with the parameters... So in theory, if you reset the tire pressue....

Need someone to confirm this --- anyone?

03-22-2006, 10:50 PM	#1
sblument Lieutenant 13 Rep 427 Posts Drives: 2006 330i Join Date: Feb 2006 Location: Champaign, IL iTrader: (0) Garage List 2006 330i [0.00]	Changing tire sizes / speedometer Question: When you order your E90 is the speedometer calibrated to your tire diameter? For example between the base 325 with its 16" wheels and the sport pkg 330 with it's 18"...is the speedometer calibrated differently? Can this be done by the dealer/maintenance shop when they change your tires? Some people on this forum have 18" summer tires and 17" winter tires...do the mechanics reset or calibrate the speedo? Boilerplate: I know similar topics have been covered before, but I searched "speedometer" and no one had previously answered the question. __________________ 2006 330i, SP, PP, fold down rear seats, sparkling graphite, black leather, metallic trim.
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03-22-2006, 11:06 PM	#2
ctgazer Major General 383 Rep 7,952 Posts Drives: a dilapidated ride Join Date: Feb 2006 Location: canada eh! iTrader: (10) Garage List 2006 e90 [0.00]	i believe that you dont have to recalibrate your speedo cause as your rim gets BIGGER, your tire thickness gets SMALLER..thus the saying, ridin on rubber bands..so when you up the size of your RIM, your profile of the tire should go smaller to keep the original diameter of the wheel and tire intact
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03-23-2006, 12:11 AM	#3
karbosshack First Lieutenant 16 Rep 350 Posts Drives: 2008 BMW 328i Join Date: Jan 2006 Location: AZ iTrader: (3)	I'm sure mines off....goin from 16-20 will change the diameter.... __________________
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03-23-2006, 07:00 AM	#4
ctgazer Major General 383 Rep 7,952 Posts Drives: a dilapidated ride Join Date: Feb 2006 Location: canada eh! iTrader: (10) Garage List 2006 e90 [0.00]	haha, michael...i believe all of ours will be if we run 20's...but u gotta love the look but you should always try and stick to the original diameter of the wheel and tire
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03-23-2006, 01:31 PM	#5
JKing3 New Member 0 Rep 19 Posts Drives: E90 Join Date: Nov 2005 Location: NH iTrader: (0)	I''d love to know this too. I'm wondering if the antilock system used in conjuction with the tire pressue monitor is what provides the speedometer with the parameters... So in theory, if you reset the tire pressue.... Need someone to confirm this --- anyone?
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