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      03-26-2014, 02:50 PM   #23
One///Em
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Originally Posted by robertm View Post
It does look fantastic but wasn't done for aesthetics. The additional rotational mass is minor negative in comparison to the huge amounts of extra grip.
Sorry, I actually disagree. Your car would probably be faster around a track with sizes closer to OEM
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      03-27-2014, 09:10 AM   #24
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Originally Posted by One///Em View Post
Sorry, I actually disagree. Your car would probably be faster around a track with sizes closer to OEM
If lap times is what you are after then wider than stock will absolutely produce a faster lap than stock sizes. There really is no debate on this point. The car has an excess of power and makes excellent use of the additional rubber.

If your looking for the ideal track setup for DEs I recommend 18s w/275s all around or 285 square with camber plates. If you're looking to competitively race the 1m on track I can't answer to that. I've never driven a 1m with full cage and proper race suspension. My gut instinct is probably wider in the rear than the front.
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      03-27-2014, 09:12 AM   #25
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Quote:
Originally Posted by robertm View Post
If lap times is what you are after then wider than stock will absolutely produce a faster lap than stock sizes. There really is no debate on this point. The car has an excess of power and makes excellent use of the additional rubber.

If your looking for the ideal track setup I recommend 18s w/275s all around or 285 square with camber plates.
285 square?? the only thing that will do is SLOW down the car with added unsprung weight....will not make it any faster.
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      03-27-2014, 05:08 PM   #26
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Quote:
Originally Posted by robertm View Post
If lap times is what you are after then wider than stock will absolutely produce a faster lap than stock sizes. There really is no debate on this point. The car has an excess of power and makes excellent use of the additional rubber.

If your looking for the ideal track setup for DEs I recommend 18s w/275s all around or 285 square with camber plates. If you're looking to competitively race the 1m on track I can't answer to that. I've never driven a 1m with full cage and proper race suspension. My gut instinct is probably wider in the rear than the front.
Ok, from experience I'd have to disagree. Drivers get obsessed with tire width. To a point width is important in getting the optimal traction footprint surface area according to the car's weight. Increasing the width too much can actually result in less traction as there is insufficient weight for the footprint to have optimal traction. You may need to put 2 bags of cement in your trunk

Adding 4-5lbs to each corner with big tires will make your car slower and probably have less/same traction
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      03-27-2014, 06:09 PM   #27
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From experience I have to disagree with both of you. My experience comes from driving and/or instructing half a dozen different 1ms on the track with various tire setups. Also my experience comes from 13 years of instructing and 12 years wheel to wheel racing.
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      03-27-2014, 06:50 PM   #28
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While there are rare cases when wider isn't faster, and even rarer cases when it's not grippier, they are in my opinion clearly the exception not the rule in our size and weight class. I generally prefer to drive on skinnier tires, and maintain the stock widths on my 1M for that reason (even going down to 18s much of the time to increase slip angle using OEM M3 wheels). However I do believe that wider would be quicker against the clock in nearly all cases, and have a fair bit of experience that proves that out. Consider that vipers run 335s with significantly less weight on them- no issues making them work.

It does depend on the type of tire, if the suspension geometry can hold the tire flat, etc, so it can get tricky. Put a 305 30 19 on a very light old 911, as I have, and you'll recognize that many variables in the cars suspension need to change in order to make the tire work. However that's going from something made for 175 70 15 bias plys to a tire that the designers wouldn't even recognize. In a 1M's tire, power and weight class it's much simpler.

I have a suspension analysis program that includes various tire models. They are generalized rather than specific, but they give a good point of reference. Going from a 265 to a 285 gives a slight but noticeable measurable increase in grip at out loadings, and importantly that grip comes at a quite a bit lower slip angle, so you get faster response. On a big track as robertm is referring to this will be compounded because you'll be less likely to overheat the compound, increasing grip further.

In the wet skinnier than we run is better. I'll argue that on the street usable feedback from the tire and slip angle is more important than width. For these reasons I like and personally recommend not going wider than stock on the street. But against the clock I agree that it's slower, even with the increased weight.

For reference, I've got cars that I compete with wearing 175 15s through 315 17s and 305 19s, with lots of stuff in between. The 175s bring some of the biggest smiles.
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      04-14-2014, 04:02 PM   #29
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Quote:
Originally Posted by ozinaldo View Post
Looks good Artemis
Keep it smooth while braking (try to avoid panic braking) for the first few hundred kms. That was the only minor issue while mine were breaking-in; they will already have better traction than your worn PS2s and after 500 to 1000 kms. the difference will be hillarious, more so on wet.
Done over 3000 km with the PSS, including some mountain passes and the German Autobahn: these puppies have grip, also in the rain.
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      04-14-2014, 09:47 PM   #30
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Quote:
Originally Posted by robertm
Been running 265/35s up front and 295/30s in back for close to a year now. About to install second set in that size PSS all around. Rubs in the front a little bit at slow speeds when turning. Like parking lots only. Not an issue for me. The newer fender liners would probably fix that.
Robert are you using those tires on stock wheels?
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      04-15-2014, 11:01 AM   #31
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FWIW - On Apex ET22 My Front end 1M conversion Rubbed with 265 PSS on low speeds in parking lots. I switched to 255s to eliminate it.
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      04-16-2014, 01:43 PM   #32
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Quote:
Originally Posted by One///Em View Post
Ok, from experience I'd have to disagree. Drivers get obsessed with tire width. To a point width is important in getting the optimal traction footprint surface area according to the car's weight. Increasing the width too much can actually result in less traction as there is insufficient weight for the footprint to have optimal traction. You may need to put 2 bags of cement in your trunk

Adding 4-5lbs to each corner with big tires will make your car slower and probably have less/same traction
I drove my car for quite a while with 265/s all around. on 18 x 10 Arc-8s (not 19s!). I have also used 275s.. When i switched to 285s I realized I actually have GRIP in the rear when in the past the tires were spinning. This was immediately something I noticed when accelerating uphill (from Wagon wheel to Ricochet at Motorsport ranch Cresson.). I didnt REALIZE how much they were spinning until i went with the 285s.

if you are speaking from Theory... then that is fine.. but from an EXPERIENTAL (no.. that's not a made up word..) perspective.. I think you are incorrect. The " optimal traction footprint" for the 1M is likely acheived with wider tires.. PARTICULARLY in the rear.

please do not ASSUME (that others are drivers " obssessed with tire width" )
I am not obsessed with tire width and nor is Robert... having both run 15s on our E30M3s for years. Like Petevb.... I would prefer to run smaller tires... First off.. they are cheaper... Second .. they have less unsprung weight.. as you mentioned.. For a long time E30 M3 owner.... that last part is VERY important..

Quote:
Originally Posted by IEDEI View Post
285 square?? the only thing that will do is SLOW down the car with added unsprung weight....will not make it any faster.



The 1M does NOT lack power. it LAUGHS at a few additional pounds of unsprung weight and says.... (scharzenegger voice) I got TORQUE baby.. get on my back and LET's GO! make no mistake... I am not saying that the unsprung weight isnt a factor... of course it is... but this car is FAR less affected by a few pounds of unsprung weight than probably any BMW before it.... ( E30M3.. E36M3.. E46 M3..E9x.. Z3..Z4.. you name it.)

harold of HPA motorsports has commented in the past as well that wider is better on the 1M... and IIRC he felt the best grip on the car would be with 10" wheels up front and 11" wheels in the rear. Personally. I didnt really subscribe to this either.. until I put 285s on the back of my car. Now... i concur. if I were racing and wanted to go FASTEST with respect to putting power the ground.. ... I would keep a staggered setup and go as big as possible in the rear.

However.. I do feel that the car * handles* best with the least understeeer by using a SQUARE setup however... and i very much recommend that to others. The car turns in SO much better with a square setup with camber plates than it does stock or on a stock setup with wider front and rear tires that it's a night and day difference. Here locally in DFW we have about 16 owners with 1Ms... and about 4-5 of us all are close friends and have shared our cars with each other so we can feel different setups.

Still not a believer? Grab a stopwatch and borrow some wheels and tires and let us know what you find from experience.

Last edited by M3 Adjuster; 04-16-2014 at 02:21 PM..
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      04-16-2014, 02:00 PM   #33
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Quote:
Originally Posted by p66 View Post
Robert are you using those tires on stock wheels?

yes. stock 19s
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      04-16-2014, 05:14 PM   #34
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Quote:
Originally Posted by M3 Adjuster View Post
I drove my car for quite a while with 265/s all around. on 18 x 10 Arc-8s (not 19s!). I have also used 275s.. When i switched to 285s I realized I actually have GRIP in the rear when in the past the tires were spinning. This was immediately something I noticed when accelerating uphill (from Wagon wheel to Ricochet at Motorsport ranch Cresson.). I didnt REALIZE how much they were spinning until i went with the 285s.

if you are speaking from Theory... then that is fine.. but from an EXPERIENTAL (no.. that's not a made up word..) perspective.. I think you are incorrect. The " optimal traction footprint" for the 1M is likely acheived with wider tires.. PARTICULARLY in the rear.

please do not ASSUME (that others are drivers " obssessed with tire width" )
I am not obsessed with tire width and nor is Robert... having both run 15s on our E30M3s for years. Like Petevb.... I would prefer to run smaller tires... First off.. they are cheaper... Second .. they have less unsprung weight.. as you mentioned.. For a long time E30 M3 owner.... that last part is VERY important..






The 1M does NOT lack power. it LAUGHS at a few additional pounds of unsprung weight and says.... (scharzenegger voice) I got TORQUE baby.. get on my back and LET's GO! make no mistake... I am not saying that the unsprung weight isnt a factor... of course it is... but this car is FAR less affected by a few pounds of unsprung weight than probably any BMW before it.... ( E30M3.. E36M3.. E46 M3..E9x.. Z3..Z4.. you name it.)

harold of HPA motorsports has commented in the past as well that wider is better on the 1M... and IIRC he felt the best grip on the car would be with 10" wheels up front and 11" wheels in the rear. Personally. I didnt really subscribe to this either.. until I put 285s on the back of my car. Now... i concur. if I were racing and wanted to go FASTEST with respect to putting power the ground.. ... I would keep a staggered setup and go as big as possible in the rear.

However.. I do feel that the car * handles* best with the least understeeer by using a SQUARE setup however... and i very much recommend that to others. The car turns in SO much better with a square setup with camber plates than it does stock or on a stock setup with wider front and rear tires that it's a night and day difference. Here locally in DFW we have about 16 owners with 1Ms... and about 4-5 of us all are close friends and have shared our cars with each other so we can feel different setups.

Still not a believer? Grab a stopwatch and borrow some wheels and tires and let us know what you find from experience.
Well written and good inputs here, they make good sense to me; thanks Mark.

As a relatively ordinary driver and with no chance of a good track around I feel that stock sizes or 255/275 sizes of good tires like PSS on stock wheels and camber plates dialed for 'more fun and agility' are all I need here.

But should I go further and on track for fastest possible, not necessarily being more fun, than I would probably choose 18' wheels with a 265/285 or 285 square set up, semi slicks and more camber than I actually have. You can't put too wide of a tire at the rear of the 1M; 295s with stock 19s, 285 with most 18s and 305 or 315 with 10.5 or 11 inch wheels would definitely give quicker times. Just plain meaningless on essentially street/back road driven 1Ms imo because those are places where stock 1M's trade mark behaviour (of playfullness) should be preserved over 'grippier/quicker'.
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Last edited by ozinaldo; 04-16-2014 at 05:33 PM..
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