Increased diameter tires e90

Blue Angel · 03-27-2011, 10:04 PM

I've been reading up on increasing the diameter of the tires on my e90 323i (Canadian model, same as a non-sport 328i I think). Currently the car has 225/45-17s front and rear on 17x8 et34 style 161 wheels.

From what I can see doing some snooping around, stepping up to a 225/45-18 should work with no clearance issues on 18x8 wheels. What I have not seen is a thread showing pics of this on an e90... there are lots of assumptions based on the sedans having more clearance than the coupe (the blue one pictured in the German forum seems to be the most popular example), and even a few pics of e90 sedans with this setup on stock ride-height suspensions.

I would like to lower the car a bit, maybe an inch, so pics (and owner feedback) of a sedan with the sport suspension and 225/45-18 tires (and 255/40-18 rears if a staggered fittment) is what I'm looking for. A non sport suspension car with lowering springs would work too.

This car will be driven by my GF 95% of the time, so dropping the suspension an inch while adding an inch to the diameter of the tires will effectively eliminate 1-1/2" of wheelwell gap while only lowering the car 1/2" closer to the ground. It will also retain the original sidewall height in case (when) she hits a pothole or several.

Thanks in advance!

Tzu · 03-28-2011, 05:24 PM

Why? Your speedo will read lower and you'll lose power felt at the butt. Whats wrong with OE diameter?

John_01 · 03-28-2011, 05:34 PM

You can increase the diameter by going to 235/40/18. That will give you a 11mm increase, which is more reasonable than the 25.4mm increase with 225/45/18. It will also fill the fenders better without needing an aggressive offset.

deanmc · 03-28-2011, 07:00 PM

There's no pictures because it's generally not a good idea to increase the diameter of your wheel/tire setup. I think the general rule of thumb is to keep the new diameter within 3% of the OEM setup so it doesn't affect your speedometer, odometer, and performance.

ceb · 03-28-2011, 08:04 PM

Changing the overall diameter is one of the few things that may actually void your warranty.

This could be considered odometer tampering and, at the very least, lead to a "odometer reading unknown" on the title.

degaby · 03-28-2011, 10:44 PM

Hey guys!
I am new to this forum and in need of some advise. I am planning to purchase a new wheel and tire set for my 2006 4Dr E90 (Stock 17" wheels) and I am looking into a stagered 18" set of Miro 111. (I love the look of the 19"s but do not care for the chopy ride). I was told that I could run 225/40 R18 on the front and 255/35 R18 on the back. Does any body have any suggestions/comments on my choice of wheel size and how it will affect handling and suspension performance?
Thank you for your time and help.

Want · 03-28-2011, 11:17 PM

My suggestion is make a new read.

Dr. G · 03-29-2011, 12:56 AM

Quote:

Originally Posted by degaby

Hey guys!
I am new to this forum and in need of some advise. I am planning to purchase a new wheel and tire set for my 2006 4Dr E90 (Stock 17" wheels) and I am looking into a stagered 18" set of Miro 111. (I love the look of the 19"s but do not care for the chopy ride). I was told that I could run 225/40 R18 on the front and 255/35 R18 on the back. Does any body have any suggestions/comments on my choice of wheel size and how it will affect handling and suspension performance?
Thank you for your time and help.

Tire size is fine

Blue Angel · 03-29-2011, 09:31 AM

Quote:

Originally Posted by Tzu

Why? Your speedo will read lower and you'll lose power felt at the butt. Whats wrong with OE diameter?

The OE diameter (25") leaves very little sidewall width when upgrading to 18" wheels. Since this car will not be driven primarily by me (my GF's car) I can't guarantee it won't hit the odd pothole. I also can't guarantee I won't lose my focus temporarily and hit one myself!

Regarding the speedo, it seems to be commonly accepted that BMWs read low from the factory, so increasing the tire diameter from 25" to 26" will add 4% to the actual speed of the car bringing it closer to the indicated speed of the spedometer.

Regarding power, this is a 2.5L 323i driven mostly by my GF... if it has enough power to get a speeding ticket it's enough for her. But to be more specific, power at the wheels will remain exactly the same as before. The effect will be the same as increasing the final drive ratio by 4%, so there will be 4% less "force" pushing on the tire's contact patch than before the change, but that lesser force will be available at up to 4% higher maximum speed, meaning the available power is the same.

My explanation may not be easy to follow, but the laws of physics don't lie.

Quote:

Originally Posted by John_01

You can increase the diameter by going to 235/40/18. That will give you a 11mm increase, which is more reasonable than the 25.4mm increase with 225/45/18. It will also fill the fenders better without needing an aggressive offset.

Actually, the 18" wheels I'm looking at have a fairly agressive offset (18x8 et20), so a wider tire wouldn't be a good idea... going to a 215/45-18 on the front has crossed my mind to give a little extra clearance... we'll see.

Quote:

Originally Posted by ceb

Changing the overall diameter is one of the few things that may actually void your warranty.

This could be considered odometer tampering and, at the very least, lead to a "odometer reading unknown" on the title.

Are there cases where this has actually happened? Seems to me this might be a real issue with trucks going significantly larger than OEM tire sizes and extending their warranties? I'm talking about a 4% change... a truck going from a 31" tire to a 35" tire would be a 13% change.

Atsnow · 03-29-2011, 10:06 AM

First 225/45/18 is too tall if you want to run oversize tires ½ an inch is the recommended maximum so the proper size to run 225/40/18

Second a little more then a 1/4 inch increase will result in a variance of 1 mph on the speedometer at 60MPH ( 1.6 KPH at 100Kph for us Canadians) which is negligible

I personally run higher tires for the increase comfort on my 335xi which is lowered 1.2 inch all around ,

Tire where installed at the dealer and no warranty issues

My winters are 215/50/17 all around and my summers are 18x8 ET20 Front with 235/40/18 18x9 ET24 Rear with 265/35/18

Here are a few pictures with the 17s wheels , Front 17 X 8 ET35 and Rear 17 X 8 ET20

GedasE92 · 06-17-2015, 01:34 PM

Hi,
Is this really the 17-inch wheels in these photos? What style?

03-27-2011, 10:04 PM	#1
Blue Angel Major 998 Rep 1,037 Posts Drives: 2011 323i and 2016 535d Join Date: Mar 2011 Location: Ottawa, ON iTrader: (0)	Increased diameter tires e90 - Pics? I've been reading up on increasing the diameter of the tires on my e90 323i (Canadian model, same as a non-sport 328i I think). Currently the car has 225/45-17s front and rear on 17x8 et34 style 161 wheels. From what I can see doing some snooping around, stepping up to a 225/45-18 should work with no clearance issues on 18x8 wheels. What I have not seen is a thread showing pics of this on an e90... there are lots of assumptions based on the sedans having more clearance than the coupe (the blue one pictured in the German forum seems to be the most popular example), and even a few pics of e90 sedans with this setup on stock ride-height suspensions. I would like to lower the car a bit, maybe an inch, so pics (and owner feedback) of a sedan with the sport suspension and 225/45-18 tires (and 255/40-18 rears if a staggered fittment) is what I'm looking for. A non sport suspension car with lowering springs would work too. This car will be driven by my GF 95% of the time, so dropping the suspension an inch while adding an inch to the diameter of the tires will effectively eliminate 1-1/2" of wheelwell gap while only lowering the car 1/2" closer to the ground. It will also retain the original sidewall height in case (when) she hits a pothole or several. Thanks in advance!
	Appreciate 0 Tweet Quote

03-28-2011, 05:24 PM	#2
Tzu Lieutenant Colonel 29 Rep 1,551 Posts Drives: 335i Join Date: Jun 2010 Location: Toronto iTrader: (1)	Why? Your speedo will read lower and you'll lose power felt at the butt. Whats wrong with OE diameter?
	Appreciate 0 Quote

03-28-2011, 05:34 PM	#3
John_01 Colonel 232 Rep 2,643 Posts Drives: E90 325i, E82 135i Join Date: Mar 2009 Location: Sydney, Australia iTrader: (0)	You can increase the diameter by going to 235/40/18. That will give you a 11mm increase, which is more reasonable than the 25.4mm increase with 225/45/18. It will also fill the fenders better without needing an aggressive offset.
	Appreciate 0 Quote

03-28-2011, 07:00 PM	#4
deanmc Captain 63 Rep 878 Posts Drives: 2006 325i Join Date: Jun 2009 Location: Orange County, CA iTrader: (15) Garage List 2006 325i [10.00]	There's no pictures because it's generally not a good idea to increase the diameter of your wheel/tire setup. I think the general rule of thumb is to keep the new diameter within 3% of the OEM setup so it doesn't affect your speedometer, odometer, and performance. __________________
	Appreciate 0 Quote

03-28-2011, 08:04 PM	#5
ceb NHTSA Nazi 28 Rep 1,983 Posts Drives: 335ix Join Date: Aug 2009 Location: MD iTrader: (1)	Changing the overall diameter is one of the few things that may actually void your warranty. This could be considered odometer tampering and, at the very least, lead to a "odometer reading unknown" on the title.
	Appreciate 0 Quote

03-28-2011, 10:44 PM	#6
degaby New Member 2 Rep 6 Posts Drives: 2006 E90 Join Date: Mar 2011 Location: Napa,CA iTrader: (1)	Hey guys! I am new to this forum and in need of some advise. I am planning to purchase a new wheel and tire set for my 2006 4Dr E90 (Stock 17" wheels) and I am looking into a stagered 18" set of Miro 111. (I love the look of the 19"s but do not care for the chopy ride). I was told that I could run 225/40 R18 on the front and 255/35 R18 on the back. Does any body have any suggestions/comments on my choice of wheel size and how it will affect handling and suspension performance? Thank you for your time and help.
	Appreciate 0 Quote

03-28-2011, 11:17 PM	#7
Want YVR 22 Rep 403 Posts Drives: A Monaco Blue Join Date: Aug 2010 Location: Vancouver iTrader: (0)	My suggestion is make a new read. __________________ mbmbmbmbmbmbmb
	Appreciate 0 Quote

03-29-2011, 10:06 AM	#10
Atsnow Captain 80 Rep 967 Posts Drives: E92 335xi, 2010 Boxster S Join Date: Sep 2007 Location: Montreal /Plattsburgh,NY iTrader: (1)	First 225/45/18 is too tall if you want to run oversize tires ½ an inch is the recommended maximum so the proper size to run 225/40/18 Second a little more then a 1/4 inch increase will result in a variance of 1 mph on the speedometer at 60MPH ( 1.6 KPH at 100Kph for us Canadians) which is negligible I personally run higher tires for the increase comfort on my 335xi which is lowered 1.2 inch all around , Tire where installed at the dealer and no warranty issues My winters are 215/50/17 all around and my summers are 18x8 ET20 Front with 235/40/18 18x9 ET24 Rear with 265/35/18 Here are a few pictures with the 17s wheels , Front 17 X 8 ET35 and Rear 17 X 8 ET20
	Appreciate 0 Quote

06-17-2015, 01:34 PM	#11
GedasE92 Registered 0 Rep 1 Posts Drives: E92 Join Date: Jun 2015 Location: Kaunas iTrader: (0)	Hi, Is this really the 17-inch wheels in these photos? What style?
	Appreciate 0 Quote