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[mlifxs]

Hi everyone,

I'm contemplating running a square setup on my '07 pre-LCI E90, with sport package and currently staggered wheels / tires.

For the square set up. I'm planning on using OEM 17" 8.5 wheels with 37 offset. I'm pretty sure I can run 255/30/17s all around without rubbing as I've pulled my pins and have M3 arms.

But, I'm wondering if there will be any issue with steering response with a wide tread on 8.5s ? Would the car "feel" better with less width all around?

thanks in advance for your thoughts.

[John_01]

Do you just happen to have 4 of the 17 x 8.5" wheels? I don't think the 325i needs 255s for grip. In your case the turn-in should be already good with the extra negative camber (without getting the 255s). Did you consider using 255/40 rear, 235/45 front?

[VTECaddict]

First of all, what is your reasoning to run square with such meaty tires up front?

[mlifxs]

Originally Posted by VTECaddict

First of all, what is your reasoning to run square with such meaty tires up front?

My thinking is: 1. I can obtain 8.5 OEM wheels cheaply. 2. A rotatable square setup is good. 3. wider fronts will be more fun for spirited driving.
Perhaps 3. is overkill for a 328i, but should I go square, would like any info on downsides / unintended consequences

[rothwem]

I've done it, using 4 rear 161s and Continental DW 255/40R17's. I'm totally stock and it fit fine. I've got two sets of staggered 161s, I'm using the 8" fronts for "winters", and the 8.5" rears for summer tires.

It definitly increased grip a ton. Steering feel took a hit, but I think it was more due to the switch from potenza runflats. I definitly felt more body roll, because it would pull more G's and overwhelm my stock suspension instead of breaking away.

I did it for the same reasons you did, tire rotatablilty and increased fun. I like the increased tire life (25k on Conti DWs and still not to the wear bars) but I'm not sure that it made the car more fun. Maybe if I was tracking the car it would make sense (with higher spring rates), but my BMW is a DD. If you want to drive to NC to get them, I'll sell the 4 rears to you.

Originally Posted by msrothwell

I've got two sets of staggered 161s, I'm using the 8" fronts for "winters", and the 8.5" rears for summer tires.

Brilliant...I'm surprised more peeps with dedicated winter setups don't consider this option when wheel shopping.

[mlifxs]

Originally Posted by msrothwell

I've done it, using 4 rear 161s and Continental DW 255/40R17's. I'm totally stock and it fit fine. I've got two sets of staggered 161s, I'm using the 8" fronts for "winters", and the 8.5" rears for summer tires.

It definitly increased grip a ton. Steering feel took a hit, but I think it was more due to the switch from potenza runflats. I definitly felt more body roll, because it would pull more G's and overwhelm my stock suspension instead of breaking away.

I did it for the same reasons you did, tire rotatablilty and increased fun. I like the increased tire life (25k on Conti DWs and still not to the wear bars) but I'm not sure that it made the car more fun. Maybe if I was tracking the car it would make sense (with higher spring rates), but my BMW is a DD. If you want to drive to NC to get them, I'll sell the 4 rears to you.

thanks for this feedback. I'm on sport suspension ride height, with more camber. Seems like some wheel manufacturers (ie Apex) think you can go 9" width wheels with 255 on the front, if pins are pulled, so I think I'm going to be okay fitment wise.

I found that going to non-RFT took away some of the steering responsiveness, even in stock width up front.

My main concern is with regard to putting that much tire width (255) on an 8.5 up front, since most people seem to go the other way (stretching some). Wondering if it kills steering feel or responsiveness....or makes the steering feel too heavy. I would think it would improve grip and braking though.

Thanks for the offer on the wheels, though I've already bought one rear...if I go forward, I'll need another. If I don't, then I'll have one for sale myself.

[Mavus]

Originally Posted by mlifxs

thanks for this feedback. I'm on sport suspension ride height, with more camber. Seems like some wheel manufacturers (ie Apex) think you can go 9" width wheels with 255 on the front, if pins are pulled, so I think I'm going to be okay fitment wise.

I found that going to non-RFT took away some of the steering responsiveness, even in stock width up front.

My main concern is with regard to putting that much tire width (255) on an 8.5 up front, since most people seem to go the other way (stretching some). Wondering if it kills steering feel or responsiveness....or makes the steering feel too heavy. I would think it would improve grip and braking though.

I run 255/40 17" on 9.5 rims square and it adds a ton of grip and improves breaking. Handling is improved also obviously. The 8.5 rim is small for this tire. You will notice that the tire will bubble on the side since the rim is narrow. You really need 9.0 or ideally 9.5 rim to provide the maximum support for the tire to handle vehicle weight and transient responses. Your steering feel will not be impacted that much if the tire has required support from the rim. Your M3 arms help also. If you get lightweight rims you will improve handling and braking by decreasing unsprung weight. You will definitely feel it. This is the best mod for these cars beside suspension.

Just my 2c ...

[mlifxs]

Originally Posted by NokTurNaL 330i

I run 255/40 17" on 9.5 rims square and it adds a ton of grip and improves breaking. Handling is improved also obviously. The 8.5 rim is small for this tire. You will notice that the tire will bubble on the side since the rim is narrow. You really need 9.0 or ideally 9.5 rim to provide the maximum support for the tire to handle vehicle weight and transient responses. Your steering feel will not be impacted that much if the tire has required support from the rim. Your M3 arms help also. If you get lightweight rims you will improve handling and braking by decreasing unsprung weight. You will definitely feel it. This is the best mod for these cars beside suspension.

Just my 2c ...

thanks for the comments. Good to know about the tire width vs wheel width. I suppose I could also consider 245 on 8.5?

Like your lightweight wheel angle. If I had the cash....

[Park2670]

Ive run Kosei K1 17x8.5 ET40 with 255/40R17 all around for track days. They fit great, provided lots of grip, and I feel didnt lose steering feel.

I loved the look (other than the ugly wheels) and enjoyed the enhanced grip for driving and tracking.

[rothwem]

Originally Posted by mlifxs

thanks for this feedback. I'm on sport suspension ride height, with more camber.

I should have mentioned, I'm at stock ride height with the sport package.

[mlifxs]

Originally Posted by NokTurNaL 330i

You will notice that the tire will bubble on the side since the rim is narrow.

When you say "the tire will bubble", are you saying it will deform under stress or that it will simply have a "bubble" or wider appearance sitting on an 8.5 vs a wider rim folks would typically use?

I certainly would be concerned about the former. If it's the latter, I guess my current rears are indicative of how it will look (kind of "meaty beefy" lol ).

[Mavus]

Originally Posted by mlifxs

When you say "the tire will bubble", are you saying it will deform under stress or that it will simply have a "bubble" or wider appearance sitting on an 8.5 vs a wider rim folks would typically use?

I certainly would be concerned about the former. If it's the latter, I guess my current rears are indicative of how it will look (kind of "meaty beefy" lol ).

Well, both really. The inadequate support from the rim will diminish handling and steering feedback. You are better off w/245 on 8.5 rim. Remember that non-rft tires have softer (regular) sidewalls. Check-out tracking section for additional details. Since you want to learn I would post your question in the tracking section and you will get all the details from experienced drivers. Make sure you do this right cause it will impact every mile you drive. :-)

[mlifxs]

Originally Posted by NokTurNaL 330i

Well, both really. The inadequate support from the rim will diminish handling and steering feedback. You are better off w/245 on 8.5 rim. Remember that non-rft tires have softer (regular) sidewalls. Check-out tracking section for additional details. Since you want to learn I would post your question in the tracking section and you will get all the details from experienced drivers. Make sure you do this right cause it will impact every mile you drive. :-)

thanks for your help on this, I definitely do not want to shoot myself in the foot.

[jjellyneck]

Originally Posted by msrothwell

I've done it, using 4 rear 161s and Continental DW 255/40R17's. I'm totally stock and it fit fine. I've got two sets of staggered 161s, I'm using the 8" fronts for "winters", and the 8.5" rears for summer tires.

It definitly increased grip a ton. Steering feel took a hit, but I think it was more due to the switch from potenza runflats. I definitly felt more body roll, because it would pull more G's and overwhelm my stock suspension instead of breaking away.

I did it for the same reasons you did, tire rotatablilty and increased fun. I like the increased tire life (25k on Conti DWs and still not to the wear bars) but I'm not sure that it made the car more fun. Maybe if I was tracking the car it would make sense (with higher spring rates), but my BMW is a DD. If you want to drive to NC to get them, I'll sell the 4 rears to you.

Great review by the way!

[Mavus]

Originally Posted by mlifxs

thanks for your help on this, I definitely do not want to shoot myself in the foot.

http://www.e90post.com/forums/showthread.php?t=651864

[John_01]

The downside of this setup is going to be the weight. OEM 17" wheels can be really heavy. So are proper sports tires with suitable stiff sidewalls.

[CJ421]

The car will turn in easier with a narrower tire up front. The 'feel' of the car is attributable to the compound/structure/tread pattern of the tire; the width (total amount of rubber) comes into play when you're using a significant amount of the available grip. There's not much of a difference in total grip between the widths you're talking about.

Personally I would keep the staggered setup and get non-directional tires so you can swap side-to-side. There's less than a 10% difference between a 235mm and a 255mm width tire. You can run a 235 on an 8" OEM wheel and a 255 on an 8.5" just fine (the latter is factory spec). For the street I run 235/265 on OEM 19" rims.
Should you go square with OEM rims, you may want to invest in some spacers to even out the appearance of using OEM rear wheels up front; it will look a little off.

RFT's work well with the standard suspension. Going to a non-RFT will improve grip (assuming the right tire) but take away some illusion of turn-in responsiveness provided by the rock-hard RFT sidewall (RFT sidewalls have very little flex so it adds to total spring rate).

Edit: Invest in some camber plates if you really want to improve the handling of the car; they aren't that expensive and running -1.5 deg. up front will noticeably improve cornering performance.

[mlifxs]

Thanks for your comments. If narrower feels better most of the time and wider brings limited benefits, only at extremes, perhaps I should rethink.

[BMWWW]

Originally Posted by CJ421

The car will turn in easier with a narrower tire up front. The 'feel' of the car is attributable to the compound/structure/tread pattern of the tire; the width (total amount of rubber) comes into play when you're using a significant amount of the available grip. There's not much of a difference in total grip between the widths you're talking about.

Personally I would keep the staggered setup and get non-directional tires so you can swap side-to-side. There's less than a 10% difference between a 235mm and a 255mm width tire. You can run a 235 on an 8" OEM wheel and a 255 on an 8.5" just fine (the latter is factory spec). For the street I run 235/265 on OEM 19" rims.
Should you go square with OEM rims, you may want to invest in some spacers to even out the appearance of using OEM rear wheels up front; it will look a little off.

RFT's work well with the standard suspension. Going to a non-RFT will improve grip (assuming the right tire) but take away some illusion of turn-in responsiveness provided by the rock-hard RFT sidewall (RFT sidewalls have very little flex so it adds to total spring rate).

Edit: Invest in some camber plates if you really want to improve the handling of the car; they aren't that expensive and running -1.5 deg. up front will noticeably improve cornering performance.

+1. There is a lot of tire-misunderstanding on this forum.
Increasing camber isn't going to increase steering response.

To be honest, most improvements that people report are due solely to the change in tire compound more than anything else. In fact, increasing your tread width actually alters your tire footprint, which can negatively affect braking/take-off a bit if you are able to isolate just this one variable--but thankfully, the change in tire compound more than compensates for this postively.

To increase grip/performance:
- better tire compound (improves every aspect of a car--actually the single most 'bang-for-buck' you can spend on a car sans ecu-tuning)
- increasing tire width will increase the ceiling for grip at the limit
- more camber = a higher ceiling at the limit
- steering response has a lot to do with weight at each corner, as well as the construction of the tire--mostly the stiffness of the sidewall. (narrower sidewalls or higher tire pressure will help improve steering response)

There's a lot more to it, but that's a very basic overview. Tires are a black-art, and there's no better example of this in action than at an autox. Where great cars with lousy tires/drivers can be beaten by $2,000 shitboxes on r-compounds + great driver.

[rothwem]

Originally Posted by John_01

The downside of this setup is going to be the weight. OEM 17" wheels can be really heavy. So are proper sports tires with suitable stiff sidewalls.

The Conti DW in 255/40R17 is lighter than the RE050 RFT in 225/45R17. The 8.5" wheel is only a pound or two heavier than the 8" wheel.

[sohlman]

I can't work out why you would want such a wide tyre for your winter set. If you want grip in snow and ice you don't want wide tyres. Also why would you want super light wheels. When winter comes so does terrible road conditions and pot holes or certainly in the UK. Thus you want the strongest wheels you can get. I buy the arguments for the summer, but for winter your car will handle worse.

I would go with what BMW designed in terms of widths for winter running. They did a lot of testing to work out what worked best.

Out of interest my winter set is 225/45/17