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[Ginger_Extract]

Enjoy the setup. Only word of warning I will interject, is that you may want to mind sidewalls on the front tires. I an also running a 255 RS3 on a 17x8.5" wheel. I have noticed that the Hankooks do not respond well to being pinched on a relatively narrow wheel, and at the absolute limit I get a nasty tire shake once the fronts have become overloaded. My guess is that with 17" wheel and 40 series sidewall, compared an 18" wheel and a 35-series sidewall, there is inadequate sidewall support for such a heavy car. YMMV.
this is actually why I will be pushing the limits and trying to fit a 17x9 up front, to give the 255s greater sidewall support and effective contact patch. A lot of the EVO and STi guys love to run 17x9.5 w/ 255s because it pretty much gives the wheel a functional level of stretch and helps with consistent performance and wear.

On the flipside, I also use Style 68's w/ a 255/40 RS3 on the rear, no load issues there. In fact, my front tires wore out before the rears did, even though I love to pitch the car sideways at autox and blaze rubber on corner exit.

[DietTab]

How much pressure are you using in yours? We've had good luck locally running 40-42 pounds on the asphalt, and 44-45 on concrete. The RS3s like air pressure. It was your setup that encouraged me to run these actually, it just seemed silly not to go with the same wheels all around

You might be running into wheelhop and not normal tire shake in the front - I encountered it with the runflats at the limit when i broke the rear loose slightly to help rotate the car. Since it basically pushes the front tires sideways at 90 degrees, they grip, skid sideways, grip, skid sideways, repeat. If you mount a gopro behind the fender you can see what the tire is actually doing. This is what it did to my runflat - took some nice chunks out of it and literally ripped the center tread into two

[DietTab]

Originally Posted by Rukuss

Nice set up, how does it handle with the 255 on all fours? Feels nice and planted I bet.

Feels good. Car rides so much nicer on these then the runflats

[lastMleft]

Originally Posted by DietTab

Feels good. Car rides so much nicer on these then the runflats

Fantastic, might be my future direction

[DietTab]

200 miles and only a very minor rub to report, over a hard dip at high speed. The area concerned is where the fender meets the front bumper, took some extra massaging/pulling. There was barely a witness mark, but I pulled extra out of an abundance of caution. Should have no further issues going forward, and certainly this would not be an issue at normal/autox speeds.

I will say that if you don't want to do any fender work, to stick with the 245 front tire.

[Kgolf31]

Dude, you're running WAY too high of pressures.

17x8.5 wheel here on 245/45 RS3s and I run 31 front 29 rear.

The statement that RS3s like high pressures is completely false. They need as low of pressures as possible.

People don't like low pressures on the RS3s because they feel like crap at that point, but it is the fastest out of the tire. You need the RS3 sidewall to deflect and load up. With high pressures sure, you get some extra response but you don't get the lateral grip.

Chalk the arrows and lower the pressure, you're running way too much

[DietTab]

Originally Posted by Kgolf31

Dude, you're running WAY too high of pressures.

17x8.5 wheel here on 245/45 RS3s and I run 31 front 29 rear.

The statement that RS3s like high pressures is completely false. They need as low of pressures as possible.

People don't like low pressures on the RS3s because they feel like crap at that point, but it is the fastest out of the tire. You need the RS3 sidewall to deflect and load up. With high pressures sure, you get some extra response but you don't get the lateral grip.

Chalk the arrows and lower the pressure, you're running way too much

Thats been the experience locally with other cars. It's a lot different conditions here then ohio, mainly track temperature. A 140 degree surface (hot ga summer on asphalt) works a lot different then a 95 degree surface Of course, the tire marker will tell you what the pressure needs to be.

[128Convertibleguy]

Originally Posted by Kgolf31

Dude, you're running WAY too high of pressures.

17x8.5 wheel here on 245/45 RS3s and I run 31 front 29 rear.

The statement that RS3s like high pressures is completely false. They need as low of pressures as possible.

People don't like low pressures on the RS3s because they feel like crap at that point, but it is the fastest out of the tire. You need the RS3 sidewall to deflect and load up. With high pressures sure, you get some extra response but you don't get the lateral grip.

Chalk the arrows and lower the pressure, you're running way too much

Tire pressure is a really strange deal on a stock or mildly modified car. When I was wheel to wheel racing, a guy with my car/tires suggested pressures that were 10 psi less than what I and others were running. Tried it.

There was no noticeable difference in my lap times. With a 10 psi change. I did have to move my turn in points a good bit back.

I'd guess the issues are effective spring rate and turn in. Maybe temperature? In some (many?) cases these may incline one to run slightly high tire pressures, in spite of the fact it compromises grip.

The more modified your car is, and the more the tires were engineered for competition, the less good high pressures will do.

[DietTab]

If you ran 29 psi on an RS3 on the local grooved concrete airstrip in the summer, you would roll that tire straight off the bead. If you ran 29 psi on an RS3 on the asphalt course here (on an actual race circuit) the same thing would probably happen.

Surface traction matters. You can't simply say (x) psi is too much or too little.

[Kgolf31]

Originally Posted by DietTab

Thats been the experience locally with other cars. It's a lot different conditions here then ohio, mainly track temperature. A 140 degree surface (hot ga summer on asphalt) works a lot different then a 95 degree surface Of course, the tire marker will tell you what the pressure needs to be.

Well, I hate to say it but the pressures are still too high. Especially with your camber it is way too much.

Originally Posted by 128Convertibleguy

Tire pressure is a really strange deal on a stock or mildly modified car. When I was wheel to wheel racing, a guy with my car/tires suggested pressures that were 10 psi less than what I and others were running. Tried it.

There was no noticeable difference in my lap times. With a 10 psi change. I did have to move my turn in points a good bit back.

I'd guess the issues are effective spring rate and turn in. Maybe temperature? In some (many?) cases these may incline one to run slightly high tire pressures, in spite of the fact it compromises grip.

The more modified your car is, and the more the tires were engineered for competition, the less good high pressures will do.

I run less rear camber than OP and I'm much, much lower still.

R-Comps are a completely different animal than street tires (if that is what you're running). However I know from a couple guys running C6 Z06 Corvettes that ran into pressure issues and were a couple pounds too high.

I'm #400 fronts/#700 rears. Am I not the typical car on this forum....maybe. I'm also probably close to one of the lightest cars on the forum still in street trim. (2981 lbs in race trim)

However, the experience with low pressures still occurred with my Z4M when I ran 235/45 and 265/40 RS3s on stock camber/stock suspension.

IIRC I was around 30 front and 28 rear. Car was 3231 lbs in race trim.

Originally Posted by DietTab

If you ran 29 psi on an RS3 on the local grooved concrete airstrip in the summer, you would roll that tire straight off the bead. If you ran 29 psi on an RS3 on the asphalt course here (on an actual race circuit) the same thing would probably happen.

Surface traction matters. You can't simply say (x) psi is too much or too little.

You sure about that statement?

Well here is 29 PSI rear tire pressure at Lincoln Airpark Airport - Concrete Surface:







You can see the car is fully loaded in all 3 pictures and surprisingly, the tire isn't flying off the car...

Ran the same pressures at Toledo Express Airport, another venue that sees National SCCA competition.


There has been extensive data with this, and the consensus is run as low as you can to achieve optimal lateral grip.

Through my data I've seen peaks of 1.4Gs easily. Previously when I mounted the wheels I started at 32 square and was only peaking around 1.3G-ish


Take my advice or not, I wouldn't tell you something unless I've done it plenty of times and know that 40+ is extremely high.

When you lower the pressures will you lose some minimal response and turn-in. You bet. However it is the best way...

My 0.02 cents


PS - For what it is worth, I actually ran Dunlop Z2s higher.

34 PSI Front, 32 PSI Rear

Wilmington Airport. Another Groved Concrete Site that was fairly rubbered in

[DietTab]

Any data is good data, so thanks for sharing. I'm sure with 700# less weight and 50% higher spring rate I could run less tire pressure too Mine is 3320 +400 lbs of driver/codriver.

I think you're misinterpreting what I have been saying also, these aren't what I have run in this car (these are new tires to me), its what others have had success with locally running the RS3 in heavier cars. I'll certainly be starting in low 30s based on your recs.

[Ginger_Extract]

Originally Posted by Kgolf31

Dude, you're running WAY too high of pressures.

17x8.5 wheel here on 245/45 RS3s and I run 31 front 29 rear.

The statement that RS3s like high pressures is completely false. They need as low of pressures as possible.

People don't like low pressures on the RS3s because they feel like crap at that point, but it is the fastest out of the tire. You need the RS3 sidewall to deflect and load up. With high pressures sure, you get some extra response but you don't get the lateral grip.

Chalk the arrows and lower the pressure, you're running way too much

Correct, I run mine pretty low, around 30ish as well.

[DietTab]

Happy to report after the little pull to the fender front, the setup is now 100% rub free.

[M3to335]

Im about to throw a set of BC Coilovers and a set of Kosei K1s with 255s off my other bimmer. I did a rough fitment on the stock suspension and its apparent the front fender will need some work, if a spacer is needed to clear the coilovers. I guess we shall see!

Someone on this forum runs this setup, correct?

[DietTab]

k1s are a 40 offset. would be about the same as mine with a 3mm spacer. you may or may not need one depending on the coilover perch

[dcaron9999]

I run a square 255/35R18 setup (stock style 261 18"x8.5" ET52 RIMS used at four corners, with 10 mm spacer in front only). I run them on stock springs and dampers. No fender rolling or pulling required. I do use Front M3 control arms which pushes the bottom of the wheel outwards, and camber plates set to -3.2* camber in the front. Rear uses stock control arms and is set for -2* camber.

I track the car often and have no issues, except for front calipers which could use better cooling. Larger wheel (stock is 18"x7.5" and 215/40R18 tire) may be blocking air from bumper ducts which doesnt help. I also use F30 brake shields and Ti brake pad shields which help slightly.

These are the style 261 RIMS that came with my 135i: http://www.bmwstylewheels.com/bmw/261.
For my square setup, I bought a second pre-owned set for under $300 and used four rear wheels ...

[DietTab]

the 35 tires have a round and not square sidewall, which gives you +1cm of clearance. just for what thats worth.

[dcaron9999]

Here's a picture to show how close I am to the strut, even with 10mm spacers. There is no rubbing with my Direzza Z-II's. Picture was taken with old 255/35R18 RE-11 tires IIRC ...

[3002 tii]

Too bad nobody makes a decent sticky street tire in 245/35-18. Running that square on a 8" width would be perfect in terms of stock fitment (but obviously I'd prefer to stuff more rubber).

[Greg FEightytwo]

Originally Posted by Dackelone

How did you get 2+ degree's of negative camber front and rear? Are you using the M3 control arm bits?

Dack

I was able to get -2.8 in the front with same set up.. M3 arms, dinan camber plates, and 1.5 eibach prokit springs. It turns so much better. I set them at 0 toe and the tread is doing well so far.

[BrokenVert]

Originally Posted by Dackelone

How did you get 2+ degree's of negative camber front and rear? Are you using the M3 control arm bits?

Dack

Dack the M3 control arms dont actually help with fender clearance issues. They add camber by pushing out the bottom of the wheel, the top still makes contact.

I found that out when doing control arms to try and make my 245 square star specs fit without rubbing on dips.

[lowbudgethero]

Originally Posted by 3002 tii

Too bad nobody makes a decent sticky street tire in 245/35-18. Running that square on a 8" width would be perfect in terms of stock fitment (but obviously I'd prefer to stuff more rubber).

PSS and the conti DWs are in that size it's going to be my next purchase, I'm going the route of running the rears on the fronts with spacers