poor handling with non-run flats?

Luky · 05-08-2012, 10:47 PM

The rear tires on my E90 335i hit the wear bars so I ordered a new set on-line to replace them. I was not really happy with the RFT and decided to get a full set of Hankook Ventus V12 Evo tires as I was previously very happy with them on my E46 330i with great wet/dry handling and decent mileage (went through three sets...)

My car has the 18" staggered set up so I ordered 225/40-18 for the front and 255/35-18 for the rear (stock sizes). As my fronts are only about 50%-70% worn I decided to leave them on for another couple of months, and just had the rears installed this past Saturday.

Now my car feels VERY loose in the rear end and wiggles all over. At 70-80mph a slight jerk of the steering makes the rear end feel like it is going to slide out as it wiggles back and forth. This is what my E46 felt like when one time when I accidentally ordered 245/45-17 for the rear when I needed 245/40-17 (the higher side wall made the rear end feel much less stable - but it my my speedo right on per my GPS...). It does drive straight hands off and does not pull so I don't think it's the alignment.

Since the car drove OK before I had the new rears mounted I wanted to know if the difference in tires (run flat with stiff sidewalls in front and non-run flat in the rear) could be causing my handling issue? Will it improve if I put the matching fronts on the car? Is this the "nature" of non-run flat tires on this vehicle? Or does it sound like I have a different issue? (like camber or bad bushings)- also I am at 60k miles... (I know my RTABs were shot in my E46 by 60k...)

Tom K. · 05-09-2012, 11:08 AM

This is why mismatching tires front to rear is a poor idea - especially with radically different sidewall stiffnesses.

While replacing RFTs with go-flats may result in a slightly mushy turn in feel, my experience is that the handling should be fine with 4 matched tires.

I'd also be very, very careful on wet pavement until you get the proper front tires mounted - at which point your handling issues should disappear.

Tom

ronmeister · 05-09-2012, 11:11 AM

Don't mix RFTs with non-RFTs...nothing good can come from it.

derrick603 · 05-09-2012, 12:39 PM

Keep in mind that new tires may still have the mold release lubricant on them. It should wear off in 500 miles or so.

Hybrid For Life · 05-10-2012, 03:03 AM

Quote:

Originally Posted by ronmeister

Don't mix RFTs with non-RFTs...nothing good can come from it.

+1, differences in sidewall thickness can screw with your balance of handling.

Quote:

Originally Posted by derrick603

Keep in mind that new tires may still have the mold release lubricant on them. It should wear off in 500 miles or so.

+1

driverman · 05-12-2012, 08:00 AM

I think 3 things are contributing to oversteer:

- RFT's in front are much stiffer than non-RFT's in rear
- mold release lubricant in rear for 1st 500 miles
- newer rear tires have more tread than fronts

I'd install the new non-RFT's in front, increase tire pressures all around 2-3 psi and take it easy for the first 500-1000 miles. Some additional stiffening will occur during the next few thousand miles.

05-08-2012, 10:47 PM	#1
Luky First Lieutenant 78 Rep 342 Posts Drives: 2016 550i M Sport Join Date: Jan 2012 Location: San Diego iTrader: (2)	poor handling with non-run flats? The rear tires on my E90 335i hit the wear bars so I ordered a new set on-line to replace them. I was not really happy with the RFT and decided to get a full set of Hankook Ventus V12 Evo tires as I was previously very happy with them on my E46 330i with great wet/dry handling and decent mileage (went through three sets...) My car has the 18" staggered set up so I ordered 225/40-18 for the front and 255/35-18 for the rear (stock sizes). As my fronts are only about 50%-70% worn I decided to leave them on for another couple of months, and just had the rears installed this past Saturday. Now my car feels VERY loose in the rear end and wiggles all over. At 70-80mph a slight jerk of the steering makes the rear end feel like it is going to slide out as it wiggles back and forth. This is what my E46 felt like when one time when I accidentally ordered 245/45-17 for the rear when I needed 245/40-17 (the higher side wall made the rear end feel much less stable - but it my my speedo right on per my GPS...). It does drive straight hands off and does not pull so I don't think it's the alignment. Since the car drove OK before I had the new rears mounted I wanted to know if the difference in tires (run flat with stiff sidewalls in front and non-run flat in the rear) could be causing my handling issue? Will it improve if I put the matching fronts on the car? Is this the "nature" of non-run flat tires on this vehicle? Or does it sound like I have a different issue? (like camber or bad bushings)- also I am at 60k miles... (I know my RTABs were shot in my E46 by 60k...)
	Appreciate 0 Tweet Quote

05-09-2012, 11:08 AM	#2
Tom K. Major General 124 Rep 5,627 Posts Drives: '07 328iT, '13 Boxster Join Date: Mar 2008 Location: Maryland iTrader: (0)	This is why mismatching tires front to rear is a poor idea - especially with radically different sidewall stiffnesses. While replacing RFTs with go-flats may result in a slightly mushy turn in feel, my experience is that the handling should be fine with 4 matched tires. I'd also be very, very careful on wet pavement until you get the proper front tires mounted - at which point your handling issues should disappear. Tom
	Appreciate 0 Quote

05-09-2012, 11:11 AM	#3
ronmeister Private 10 Rep 97 Posts Drives: 11' 335i Xdrive Join Date: Sep 2010 Location: Canada iTrader: (0)	Don't mix RFTs with non-RFTs...nothing good can come from it.
	Appreciate 0 Quote

05-09-2012, 12:39 PM	#4
derrick603 Captain 55 Rep 592 Posts Drives: 2007 335i Join Date: Jun 2010 Location: Fremont, CA iTrader: (0)	Keep in mind that new tires may still have the mold release lubricant on them. It should wear off in 500 miles or so.
	Appreciate 0 Quote

05-12-2012, 08:00 AM	#6
driverman Captain 38 Rep 715 Posts Drives: 2008 328i 6MT - SOLD Join Date: Nov 2008 Location: El Dorado Hills, CA iTrader: (0)	I think 3 things are contributing to oversteer: - RFT's in front are much stiffer than non-RFT's in rear - mold release lubricant in rear for 1st 500 miles - newer rear tires have more tread than fronts I'd install the new non-RFT's in front, increase tire pressures all around 2-3 psi and take it easy for the first 500-1000 miles. Some additional stiffening will occur during the next few thousand miles.
	Appreciate 0 Quote