[GCinFLA]

Originally Posted by TANG2864

So, I've had oem 437m's with continental extremecontacts dw summer performance's since 2500 on my odometer, and now i have a little over 35k.

once I put on the 437's from a m4 with stock tire specs, i noticed that the camber of the wheels looked more slanted. from looking at the rear, it had a very aggressive stance. I drove like this all the way till about 27000 miles. psi were kept around 33 after having them at 35-38, very bumpy and stiff.

I did a lot of burnouts on these tires and wheels and in the end, it lasted me just about 25k miles. front wear was almost pretty even, outside 10% of tread was still looking brand spankin new, inside was worn a tad bit more, definetly had at least 10k+ more miles to the fronts, but i changed the tires due to a screw/patch so i just wanted new fronts. The rears, by 25000k, i noticed massive wear on the inside 35% of tread, outside of tread looked almost like they were driven less than 2k miles. by 26k the inside 35-40% tread was bald. by 27k and some suicide burnouts, ribbons were showing on the inner inner side of tire. outside of tire still looked like only used for 5k, still had deep grooves, didnt measure depth though.

so for the next set of tires, same as oem m4 tire sizes, still conti extremecontacts, i went to get an alignment to 1. adjust for the lowering springs i installed, and 2. to maximize the life of my tires after seeing the massive uneven tread wear form last set. I dont remeber what the alignment specs we went on was, but for the fronts,we kept it the same as 435i oem alignment specs, but the rears were pulled in .8 degrees. and from 27k to now 35k, when i inspect with the naked eye, the contact patch is much better from the back. wheel wear looks pretty even, outside still wears less, but that's expected, but the contact patch looks much better with the alignment adjustment. I lowered the front psi to 31psi and rears are at 33. as of 27k-35k now, everything feels and looks good, but i havent been driving hard on these tires so I can't tell for sure how the wear is, but looks much more even.

2015 435i stock suspension for the first 27k, then now im lowered on hr sport springs.

i find the ride with 31f/33r psi pretty comfy.

Did your bimmer come with 18" or 19".

What OEM tire pressure is recommended in your door panel?

[GCinFLA]

I have the distinct impression most who install 437m on F3x vehicles and F3x specs are going to be buying new tires pretty fast.

Now the question will be....will more admit it.

[Musashi]

Originally Posted by TANG2864

im just over 35k now, been modded for at least 20k i believe, and no issues whatsoever related to the mods. had the idrive crap out on me once, replaced under warranty but had nothing to do with the FBO and jb4.

I just saw your post or could have provided input. The camber you had initially was TOO AGGRESSIVE. Reading your first post, I thought "Inside wear rear." You only go close to -2deg IF you regularly track your car, or you compromise normal day spirited handling. In my case, found out that -1.3 to -1.5 max was perfect to prevent outside wear.

The pressure is another thing. Going too low, esp on 20", compromises the car's performance. The best numbers I had were 4.3 to 4.4 s 0-60s. Fiddle with the pressure and the number go up. In my case, 20" were brutal in Canada, where road issues- just once or twice a year- meant one bent wheel and vibrations.

Alignment is a must. After going to Ray's top grade wheels, 235/40 -19 AND 275/35-19, WIDER, saved 26 lbs vs 405M and 43 lbs vs 361M, handling, everything is improved dramatically.

So to improve handling, the true solution is -1.3deg, close to recommended PSI (or below for non RFT's), and suspension tuneup e.g. Dinan.

[Musashi]

Originally Posted by Kabrich

steelerfan and I had a very interesting private chat via text for several hours on Tuesday night about Summer Tires/437m/F30.

steelerfan 's rear MPSS (275) tread on 437m are just about gone after roughly ~13k miles.

It lead to a long discussion of what is the proper tire pressure for 437m on f30s?

Here are some of the reasons that this does not seem as straight forward as on would think.

The Door Sticker for my F30 with 19" 403m are:
Curb Weight 3,560-3,979
Mine is 3,825
225/40/19 front 35
255/35/19 rear 38

M4
Curb Weight 3,530-4,055
255/35/19 front 32 (though owners manual specifies 31)
275/35/19 rear 32
Source: http://f80.bimmerpost.com/forums/sho...php?p=21151242

M3
Curb Weight 3,540
255/35/19 front 32 (though owners manual specifies 31)
275/35/19 rear 32
Source: http://f80.bimmerpost.com/forums/sho...php?p=21151242

M2
Curb Weight 3,450
245/35/19 front 35
265/35/19 rear 35
Source : http://f87.bimmerpost.com/forums/sho...php?p=21151245

Given the differences, we both came to the conclusion we had no idea what the proper PSI should be for 437m on a F30.

So, Can anyone add any insight as to correct PSI? Does it change depending on tire/wheel size width or diameter....especially with 437m?

I finally figured it out. You can weight your car at a station, but, usually, BMW is right on. The sitcker tire pressures, designed for the initial tires, determines the weight per axle, per wheel, and is a ratio of weight vs tire load. So, example, 225 35 20 Pirelli runflat, at 1000/1360 lbs x max50 PSI gives you the 38 PSI front. But put a Michelin PSS4, with a load of 1560, then your lowest PSI is 34 due to the load index, but does not mean it HAS to be so.

Rear is where it gets interesting. Non M cars have understeer built in. xDrives are also heavier in the front, by a bit. Consequently, even though the calculator would reveal ridiculously low numbers for the rear (using the formula, my 275 Michelin should be 28 PSI), in reality it has to be stiffer than the front to compensate for the understeer. In the 20" format, they added 6 PSI. On a Michelin, I would start with 4. So if you have 34 front, rear should be no more than 37-38. If lowering front to 33, rear 36-37. However, I tried 32 front, and it was SOOO MUSHY. Finally, if 37 is too high for the rear, you get what a lot of people ended up having, 34-35 all around.

As if not enough, the suspension also plays a role. More body roll in non-M cars means that the lower pressure equals, as I had, outer wear on my rears. Had to decrease camber, and keep the pressure a bit higher, and it resolved it, but took me 2 Pirelli sets.

SO what works for a lighter M does not work for a non M. And if you add max load, with people- an unusual way of driving an M, then PSI is most likely higher in the book.

In addition, M's are meant to be tracked, and many do track them. Pressure goes up a lot, so that M could be skirting 36 front 40 rear, even if starting at 32. So if driven in normal conditions, spirited, am not sure I would use 32.