Too Wide Tires for 1M ?

[guyp]

The original 1M Wheels do well on high speed track with Michelin Sport CUP + on OEM size.
I have tried 18x10 with 265-35-r18 square and it drive nicely with R-Compounds.

but My last wheel/Tire setup doesn't do the job overs 140kph. The car move sideways a bit, il Wooble, the stock suspension seems soft with this setup . I feel the car roling more than usual. I don't like the feeling ! i have tried pressures from 29to 40 without succes. help me !

The wheels a Lignt Enkei 18x10 offset 25, the tires are almost new Toyo R888
front: 255-35
rear: 295-30

What could be wrong ?
Thank's

[1SerieStud]

Simple: you screwed around with the wheel-tire-suspension geometry that the M engineers designed for this car. Leave perfect alone. Not sure why people buy the 1M to change exactly what sets the car apart from a 135i...oh well, to each his own

[rad doc]

Originally Posted by 1SerieStud

Simple: you screwed around with the wheel-tire-suspension geometry that the M engineers designed for this car. Leave perfect alone. Not sure why people buy the 1M to change exactly what sets the car apart from a 135i...oh well, to each his own

This answer is just silly! The BMW engineers built the car to perform highly within the limitations of a daily drive/consumer vehicle. There is no reason that one can not improve the car, particularly in regards to track performance. I LOVE my car but there is always room for improvement.

Why come to a forum that is largely here to support customization and thread crap? Would you prefer we all just sit around and talk about how identical our cars are?

[1SerieStud]

Originally Posted by rad doc

This answer is just silly! The BMW engineers built the car to perform highly within the limitations of a daily drive/consumer vehicle. There is no reason that one can not improve the car, particularly in regards to track performance. I LOVE my car but there is always room for improvement.

Why come to a forum that is largely here to support customization and thread crap? Would you prefer we all just sit around and talk about how identical our cars are?

A few things:

1) The M division of BMW is more than about daily driving. There is a much more pronounced enthusiast twist to every car that ends up with an M badge on it.

2) The answer is not silly. Go ahead, hit the back button and see the multiple threads of people replacing springs, compromising a fully engineered M suspension in order to lower the car an inch. If you know anything about suspension geometry, then you know that this type of modification yields no performance improvement.

3) You can do whatever you want to your car....you have as much freedom to do that as I do to express what I think. Apparently your concern is not performance, it's individuality and making your car different from the next.

4) Yes there is always room for improvement, however, I can guarantee that the stock M suspension/wheel-tire package is more than enough for 99% of the people on these forums...gimme a break!

5) I don't "thread crap"...but if that is your opinion about my post, then you're welcome not to read it or digest it, trust me I won't be offended if you particularly don't read my posts.

[rad doc]

1. Agreed. There is still compromise built into the car. Regardless of M division it is still a mass produced car with limitations. Think clutch delay valve. Huge improvement without that!

2. Agree with lowering springs. But original post was about wheels and tires. 18 inch lightweight wheels likely would provide a performance improvement on the track.

3. An incorrect assumption. The items are not mutually exclusive either. One can individualize their car without sacrificing performance.

4. Likely true but again an assumption relative to the original poster whom you have no idea his abilities and needs.

5. No, I don't want to ignore your posts. I like differing opinions. But just didn't feel your response was necessary in this particular instance.

[Dan Parker]

OP, I'm a bit confused by something you said. You talk about a square setup and then finish by stating different tire sizes front to rear. You fit 295's in the rear? What size wheel are the 295's on? That's a lot of tire on the rear, and a lot on the front as well. On stock suspension you may be asking too much with the significant increase in grip. The sidewall on your 18's is going to be more compliant then the stock (somewhat stretched) 19's which could add to the floaty feeling also.

[abisson]

What could be wrong? Putting 295 on a 1M. Hell, even a 997 4CS has 305 stock in the rear. Why would you do 295? Dan and Stud and perfectly right.

[M3 Adjuster]

Agree.. The answer is simple.. you went to extreme a setup...? Why did you get rid of a comfortable setup in the 265/35/18 on every corner to a setup so much wider at the rear? You will definitely increase rear grip, causing more oversteer, in a chassis that is already biased towards oversteer. I can definitely see that the car might tramline and definitely understeer on corner entry... with likely more oversteer from mid corner to exit. sounds like you should go back to the 265/35/18s.

[luial]

Originally Posted by M3 Adjuster

sounds like you should go back to the 265/35/18s.

I think you mean 265/35-19

How about going one size wider in the rear (275/30-19), would it be ok?

[marcel b]

Originally Posted by M3 Adjuster

Agree.. The answer is simple.. you went to extreme a setup...? Why did you get rid of a comfortable setup in the 265/35/18 on every corner to a setup so much wider at the rear? You will definitely increase rear grip, causing more oversteer, in a chassis that is already biased towards oversteer. I can definitely see that the car might tramline and definitely understeer on corner entry... with likely more oversteer from mid corner to exit. sounds like you should go back to the 265/35/18s.

wider tires in the back means more grip in the back and a decrease of oversteer / increase of understeer.

[RimasRS]

Just simple question... Which suspension parts has to be improved to eliminate sideways floating on wider tires??? Would sway bar could help or some other parts?

[Dan Parker]

That's a problem. It isn't a simple question. Stiffer, lower suspension should help, in theory, but then you lessen the suspension travel.
Do you have any pics of the 295's on the rear?

[bmw13]

Originally Posted by 1SerieStud

A few things:

1) The M division of BMW is more than about daily driving. There is a much more pronounced enthusiast twist to every car that ends up with an M badge on it.

2) The answer is not silly. Go ahead, hit the back button and see the multiple threads of people replacing springs, compromising a fully engineered M suspension in order to lower the car an inch. If you know anything about suspension geometry, then you know that this type of modification yields no performance improvement.

3) You can do whatever you want to your car....you have as much freedom to do that as I do to express what I think. Apparently your concern is not performance, it's individuality and making your car different from the next.

4) Yes there is always room for improvement, however, I can guarantee that the stock M suspension/wheel-tire package is more than enough for 99% of the people on these forums...gimme a break!

5) I don't "thread crap"...but if that is your opinion about my post, then you're welcome not to read it or digest it, trust me I won't be offended if you particularly don't read my posts.

+1

Also... BMW equips their 1M safety car with 285 in the rear and 265 up front. If I were to go bigger(which I probably will) that is what I would go with. Again, M knows what they are doing. But if your vehicle is intended for show vs performance power to you. I personally will not mess with anything unless there is only substantial improvement, but again to each their own.

[Pete_vB]

Originally Posted by guyp

The wheels a Lignt Enkei 18x10 offset 25, the tires are almost new Toyo R888
front: 255-35
rear: 295-30

What could be wrong ?

No experience on this car, but a quick search indicates you went from a 31mm to 25mm front offset? I believe BMW has a small positive scrub-radius on the 1M, which you may have (edit: ) significantly increased with your new wheels. You can't address that with a spacer, so it's difficult to test, but a wheel with more offset might help if you could try one.

Otherwise, this generally sounds like an alignment issue. You didn't lower the car or make any other changes that might have changed alignment?

Originally Posted by M3 Adjuster

wider at the rear? You will definitely increase rear grip, causing more oversteer

I think you mean understeer...

[Ohcrap]

The reason I suspect he's running 295/30's is that with R888s, that's the only size he can run with his 255/35's to keep the tire diameter the same - in this case 25.1 inches. If you ran 265's with 285's on this tire, the front tire would be a larger diameter than the rear which would cause havoc with your stability control system as it would constantly think the rear tires were losing traction and the car would cut power to correct what it perceives as a traction problem.

I'm currently trying to figure out best setup myself, also on 18's (9.5's & 11s), also for track use and as I have a sponsorship from Toyo, also on R888's.

Agree at this point that on stock suspension your current setup may be a bit aggressive, but the custom wheel folks I've talked to thus far seem to think that with a good racing coilovers/camber plates etc, the setup you're running would indeed work. In fact, that is the exact tire set up CCW said they'd run as long as the 295's didn't have any clearance issues. Of course an easy option, would be to just run a square setup with the same tire all the way around (cheaper too). [we're doing some crazy power mods, that's why I want huge meat in the rear]

I'm on my way to Piper Motorsports now, and have a call scheduled with Toyo and Moton this afternoon to discuss options so I"ll share what I learn.

[FLEX///M]

I've actually ran 265,275,285, and 295 on my Clockwork Orange. By far the best looking tires are 295. I had no rubbing whatsoever. The thing looked as beastly as could be. CHUNK!

However, NO tire size out of all those had the performance of the stock 265. Performance wise, it is by far the best size. Now I just run different sizes. 295 for meets, and 265 for everything else. I love showing off the car with the chunk. But I won't sacrifice the fun that 265 gives me for nothing.

Just my 2 cents from my experience.

[guyp]

the 295x30R18 on Enkei 18x10 offset 25

My suspension is stock and i forgot to try with a full thank of gaz if the problem is less severe.

I have many set of wheels on hands
-one set with OEM 19 wheels and OEM PS2: ok balance and low grip
-One set of 19 OEM wheels and Michelin CUP + OEM size: ok balance, fair grip
-One set of 19 OZ wheelsx10 and 265-35r19 square Hossiers R6: ok balance, great grip
-One set of 18 Enkei 18x10 offset 25 rear 295x30r18 R888, 18x8,5 offset 38 front with 255x35r18 : bad balance on high speed, good grip and no more crasy oversteer.
note: i am on a Canadian Toyo sponsership race program, and i woult like to find a fair setup with my stock 1M engine and suspension.

Keep sending advices.
Guy

[Pete_vB]

Originally Posted by guyp

-One set of 18 Enkei 18x10 offset 25 rear 295x30r18 R888, 18x8,5 offset 38 front with 255x35r18 : bad balance on high speed, good grip and no more crasy oversteer.

So the front offset is actually 38 vs 31 stock, so you took out 7mm of scrub, likely putting you close to zero or actually negative scrub radius. You don't want negative scrub, you want to stay somewhat positive to preserve stability and steering feel. Try adding a 5-7mm or 1/4" spacer up front and see if that helps.

Also, if I understand it right you don't have issues with high speed balance mid-corner, more straight-line stability?

[Dan Parker]

+1 (what Pete said)

[terivera]

Originally Posted by Dan Parker

+1 (what Pete said)

I am looking for a track wheel setup and I have been told that 18 X10 with 25mm offset should be perfect running 275 X35 all square.

[terivera]

Originally Posted by terivera

I am looking for a track wheel setup and I have been told that 18 X10 with 25mm offset should be perfect running 275 X35 all square.

Sorry i failed to mention 1 series m coupe arrives next week, no real rush as we probably won't have track days till spring here.

[robertm]

Originally Posted by terivera

I am looking for a track wheel setup and I have been told that 18 X10 with 25mm offset should be perfect running 275 X35 all square.

Where did you hear that? A lot of people are wondering how wide we can go with a square setup. Also, at max width up front tire brand becomes important too. Not all 275/35s are created equal by a long shot.

From what I've read on here so far that may be pushing it up front. Please if you have actual tried and proven data by all means share!