A few questions about changing to non-RFT

SharpPointyStick · 05-22-2010, 12:52 AM

I currently have Style 155 rims (16x7 ET34) with 225/50 R16 Bridgestone Potenza RFT.

I am thinking on replacing with non-RFT, but have a few questions;

Is there any detrimental effect to the car (suspension, braking etc) when changing to RFT?
Can I go with a wider tire then 225, for more rubber on the road without spacers or rolling rims? How would I figure out maximum width?

HighlandPete · 05-22-2010, 06:51 AM

I presume you are not changing to soften the ride? Because that is what most do it for. The direct size swap will soften the ride. From experience in the UK on standard suspension (not M-sport) the damping is a bit soft in some conditions, on non run-flats. Steering response is not quite as sharp.

But increasing the tire width on the same rims, (don't forget the aspect ratio), on non run-flats will just be worse, could feel very soggy and lacking in lateral response.

HighlandPete

SharpPointyStick · 05-22-2010, 05:30 PM

Quote:

Originally Posted by HighlandPete

I presume you are not changing to soften the ride? Because that is what most do it for. The direct size swap will soften the ride. From experience in the UK on standard suspension (not M-sport) the damping is a bit soft in some conditions, on non run-flats. Steering response is not quite as sharp.

But increasing the tire width on the same rims, (don't forget the aspect ratio), on non run-flats will just be worse, could feel very soggy and lacking in lateral response.

HighlandPete

I assume the ride will feel softer due to the side wall of non-RFT not being as stiff as RFT? So going to a larger diameter rim with a lower profile non-RFT would counter the softer ride?

Is the softer ride and less responsive steering response very noticeable?

I currently have the Bridgestone Potenza and I am thinking of replacing with a Ultra High Performance or High Performance All Season.

Gary@TireRack · 05-25-2010, 02:10 PM

Quote:

Originally Posted by SharpPointyStick

I assume the ride will feel softer due to the side wall of non-RFT not being as stiff as RFT? So going to a larger diameter rim with a lower profile non-RFT would counter the softer ride?

Is the softer ride and less responsive steering response very noticeable?

I currently have the Bridgestone Potenza and I am thinking of replacing with a Ultra High Performance or High Performance All Season.

Yes, the lower profile will help negate some of the loss of steering response but should still give a softer ride than the oe RFT tires.

While the difference should be noticeable, I would not say it is dramatic.

Tires
http://www.tirerack.com/a.jsp?a=AH8&...ires/index.jsp

SharpPointyStick · 05-25-2010, 07:00 PM

I am thinking now of upgrading the rims to 17" ASA GT1. Dont want to go any larger mostly due to increased cost of wheel & tire, also I dislike the brake rotor looking too small (dont have $2000+ for a Bigger Brake Kit)

Then wrap them in Michelin Pilot Sport A/S Plus sizes;

Front: 225/45ZR17
Rear: 255/40ZR17

I assume that the above sizes are stock for a 2006 325I (E90) c/w sports edition? Should fit on a 2006 323i (E90) c/w sports edition? The rear 255/40ZR17 are not listed on my cars door sticker.

Firefly6 · 05-25-2010, 09:53 PM

The 17" wheels won't give as harsh a ride as 18 or 19" for sure. 225/45-17 is the standard size on 330 and 335 e90s. I don't know what your new offsets would be, so I don't know if rubbing could be an issue with the 255s.

SharpPointyStick · 05-25-2010, 11:55 PM

Ran the calculator at the top of this forum.

Stock wheels = Type 155 (16x7 ET34 225/50 R16) - I assume 34 = offset (mm)?

With the new rims and tires;

Fronts (17x8, 40mm offset, 225/45ZR17);

19mm LESS clearance on the strut side, and the outside edge of the wheel will EXTEND an extra 7mm
Difference in diameter (in.) - 0.114
Percent Difference 0.457

Rears (17x8, 40mm offset, 255/40ZR17)

19mm LESS clearance on the strut side, and the outside edge of the wheel will EXTEND an extra 7mm
Difference in diameter (in.) - 0.173
Percent Difference 0.692

Anyone running the same size tire? Any issues? What tire size are people using with 17" rims? The sizes above are from tirerack.com for a 2006 325I E90 with sports package

Can any suggest any other rim manufactures, with a similar look to the ASA GT1. Just so I can do some comparison shopping

05-22-2010, 12:52 AM	#1
SharpPointyStick Second Lieutenant 35 Rep 273 Posts Drives: 2006 Alpine White 323i (E90) Join Date: Jun 2009 Location: Vancouver BC iTrader: (2)	A few questions about changing to non-RFT I currently have Style 155 rims (16x7 ET34) with 225/50 R16 Bridgestone Potenza RFT. I am thinking on replacing with non-RFT, but have a few questions; Is there any detrimental effect to the car (suspension, braking etc) when changing to RFT? Can I go with a wider tire then 225, for more rubber on the road without spacers or rolling rims? How would I figure out maximum width?
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05-22-2010, 06:51 AM	#2
HighlandPete Lieutenant General 6548 Rep 15,857 Posts Drives: BMW F11 535i Touring Join Date: Mar 2007 Location: Scotland, Highland Region iTrader: (0)	I presume you are not changing to soften the ride? Because that is what most do it for. The direct size swap will soften the ride. From experience in the UK on standard suspension (not M-sport) the damping is a bit soft in some conditions, on non run-flats. Steering response is not quite as sharp. But increasing the tire width on the same rims, (don't forget the aspect ratio), on non run-flats will just be worse, could feel very soggy and lacking in lateral response. HighlandPete
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05-25-2010, 07:00 PM	#5
SharpPointyStick Second Lieutenant 35 Rep 273 Posts Drives: 2006 Alpine White 323i (E90) Join Date: Jun 2009 Location: Vancouver BC iTrader: (2)	I am thinking now of upgrading the rims to 17" ASA GT1. Dont want to go any larger mostly due to increased cost of wheel & tire, also I dislike the brake rotor looking too small (dont have $2000+ for a Bigger Brake Kit) Then wrap them in Michelin Pilot Sport A/S Plus sizes; Front: 225/45ZR17 Rear: 255/40ZR17 I assume that the above sizes are stock for a 2006 325I (E90) c/w sports edition? Should fit on a 2006 323i (E90) c/w sports edition? The rear 255/40ZR17 are not listed on my cars door sticker.
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05-25-2010, 09:53 PM	#6
Firefly6 Lieutenant 13 Rep 412 Posts Drives: 2018 330i Xdrive Join Date: Aug 2007 Location: New Jersey iTrader: (2)	The 17" wheels won't give as harsh a ride as 18 or 19" for sure. 225/45-17 is the standard size on 330 and 335 e90s. I don't know what your new offsets would be, so I don't know if rubbing could be an issue with the 255s.
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05-25-2010, 11:55 PM	#7
SharpPointyStick Second Lieutenant 35 Rep 273 Posts Drives: 2006 Alpine White 323i (E90) Join Date: Jun 2009 Location: Vancouver BC iTrader: (2)	Ran the calculator at the top of this forum. Stock wheels = Type 155 (16x7 ET34 225/50 R16) - I assume 34 = offset (mm)? With the new rims and tires; Fronts (17x8, 40mm offset, 225/45ZR17); 19mm LESS clearance on the strut side, and the outside edge of the wheel will EXTEND an extra 7mm Difference in diameter (in.) - 0.114 Percent Difference 0.457 Rears (17x8, 40mm offset, 255/40ZR17) 19mm LESS clearance on the strut side, and the outside edge of the wheel will EXTEND an extra 7mm Difference in diameter (in.) - 0.173 Percent Difference 0.692 Anyone running the same size tire? Any issues? What tire size are people using with 17" rims? The sizes above are from tirerack.com for a 2006 325I E90 with sports package Can any suggest any other rim manufactures, with a similar look to the ASA GT1. Just so I can do some comparison shopping
	Appreciate 0 Quote