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      02-08-2018, 08:02 PM   #1
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Max rubber on the M2?

Hey guys.

I have a conversation going with Apex (http://f87.bimmerpost.com/forums/sho...5#post22760045), but I wanted to open it up to everyone.

Most of us are a little lowered and are running negative camber. This limits us to about 275/35/18 in the front, but I should be able to get a 285/30 or 295/30 to fit in the back with their new FL-5 10.5” wheel. Have any of you guys ran these combos on this or other cars?

I’m trying to figure out if the gain in rear rubber is offset by negative impacts to handling or the way the differential works. This isn’t a square/stagger question, but a wider/lower diameter rear vs front question.

The reason I’m looking at these sizes is bc these are the RE-71R and R7 sizes in this range.

Thanks.

------------------------------
Quick update:

I ran 265/35/19 & 295/30/19 Hoosier R7s on the car at an open track day last week. I believe this is the Max Rubber you can get on a track prepped M2 with camber and lowered suspension!

I originally tried 295/35/19 R7s in the rear, but they were too tall and had to go 295/30s. They don't make 265/30 R7s, but the balance was still good front to rear and there was tons of grip and it was a blast!

The 265/30/19 & 295/30/19 Trofeo R setup I tried on track were great, as well. For cheaper tires, I think I can fit a 305/30/19 RE-71R in the back, but I probably won't try that until next year.

You can find my suspension and wheel specs in the thread if you're trying to figure this out, as well.

———————————————-

Latest update:

On my 19” track setup that I used for the last two years I ran Trofeo’s, Cup 2, R888R, RE-71R, and R7s, and was able to run 265/30-35 in the front and 295-305/30 in the rear.

I am going back to 18s so I can run NT01, AR1, A052, Toyo RR, and Pirelli slicks.

Crazy thing is going to the forged EC-7 18’s with A052’s will save 30lbs of rotational unsprung weight, vs my 19” VMR’s (1/2lb heavier per wheel than 19” EC-7) and RE-71Rs.

The wheel/tires I’m comparing for my setup are VMR 710FF 19x9.5 ET33 (with 3mm spacer) and 19x10.5 ET45 with 265/35/19 and 305/30/19 RE-71R’s, vs Apex Forged EC-7 18x10 ET25 and 18x10.5 ET40 with 265/35/18 and 295/35/18 A052’s.

Four width size differences was too much for good balance, but 2-3 width difference has been good in my other staggered setups, so looking forward to 265/295 and 275/295-305 with the 18’s.

I just need to make sure a 305/35/18 will clear with ET40 and lowered 3/4” in the rear. It’ll be a while before I test it bc of all the track events being shut down, but I’ll post an update when I do.

Last edited by ZM2; 09-20-2020 at 11:40 PM..
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      02-08-2018, 10:25 PM   #2
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I've been running 295s on the stock rear rims for over a year. No rubbing.
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      02-09-2018, 08:31 AM   #3
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Quote:
Originally Posted by DrKevM5 View Post
I've been running 295s on the stock rear rims for over a year. No rubbing.
18s in the size ranges were talking about have more rubber on the ground, but Ill run thru 19 wheel and tire specs this weekend to see if any make sense for a track setup.

Thanks.
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      02-09-2018, 09:25 AM   #4
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Great thread. I'm genuinely disappointed with the lack of a decent footprint for the M2.

Have you looked at the BFG R1?

It should be available in 285/30/18. I use them on 18X10 wheels all around on my 1M, and on my car the 315/30/18 fits out back on a 10.5" wheel. .

I have found that the shoulder design of the BFG helps allow a lower, wider tire.
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      02-09-2018, 10:01 AM   #5
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Quote:
Originally Posted by M3 Adjuster View Post
Great thread. I'm genuinely disappointed with the lack of a decent footprint for the M2.

Have you looked at the BFG R1?

It should be available in 285/30/18. I use them on 18X10 wheels all around on my 1M, and on my car the 315/30/18 fits out back on a 10.5" wheel. .

I have found that the shoulder design of the BFG helps allow a lower, wider tire.
Nice. Ill take a look. Apex is concerned about the 1.5 diameter drop from the OEM 265/35/19 rears to the 285/30/18, so maybe a 315/30/18 is better. Will do some measuring this weekend.
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      02-09-2018, 10:11 AM   #6
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Quote:
Originally Posted by ZM2 View Post
Quote:
Originally Posted by M3 Adjuster View Post
Great thread. I'm genuinely disappointed with the lack of a decent footprint for the M2.

Have you looked at the BFG R1?

It should be available in 285/30/18. I use them on 18X10 wheels all around on my 1M, and on my car the 315/30/18 fits out back on a 10.5" wheel. .

I have found that the shoulder design of the BFG helps allow a lower, wider tire.
Nice. Ill take a look. Apex is concerned about the 1.5 diameter drop from the OEM 265/35/19 rears to the 285/30/18, so maybe a 315/30/18 is better. Will do some measuring this weekend.
285/30/18 on a 10" in the front is what I run in my 1M all around. I'm not a fan of staggered setups because of the $$$ lost in rotation plus many other reasons and i realize why you stated that isn't part of this discussion. It's about what's the *max contact patch* can you get on each corner of this baby.

If you can fit a 315/30/18 on a 10.5 inch wheel in the rear then do it.

Putting my friends 10.5 in wide wheels with 315/30 finally got all the power to the ground on full acceleration. It was amazing the difference. The 1M can actually fit 335s. (Giggle)
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      02-09-2018, 10:26 AM   #7
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I found some photos. The new Tire is the Maxxis RC-1 in 275/35/18 and the worn tire is the BF Goodrich G Force R-1 in 285/30/18.
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      02-09-2018, 10:44 AM   #8
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In the photos above , it shows there is a lot of difference between the rounded edge of the Maxxis tire versus the squared off flat edges of the BFG tire.

The BFG contact patch literally goes to the edge of the tire whereas the Maxxis does not because of roundness in the carcass and tire mold.

The R1s In 285/30/18 stack more reliably for storage because they are flatter, and they literally have a smaller diameter which makes fitting them inside the rear of my 1M easier than the 275 Maxxis.

Hoosier seems to be a flatter shape as i recall but nothing like the BFG.
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      02-09-2018, 10:59 AM   #9
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This is all great info!

Some folks still think the 285/30/18 is too short for the M2, so I’ll look at the wider (making them slightly taller) 18s on 10.5s and see what I can come up with.

Thanks.
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      02-09-2018, 11:44 AM   #10
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Quote:
Originally Posted by DrKevM5 View Post
I've been running 295s on the stock rear rims for over a year. No rubbing.
What size are you running up front?

Got any pics?

Last edited by AndrewC1989; 02-09-2018 at 11:51 AM..
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      02-09-2018, 11:49 AM   #11
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245s in front
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      02-09-2018, 11:50 AM   #12
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245s in front
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      02-09-2018, 11:54 AM   #13
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Quote:
Originally Posted by DrKevM5 View Post
245s in front
Thanks.

I'm swapping tires on the stock wheels in the spring and was initially thinking of going PS4S on stock m3 sizes and keeping my spacers but now i'm kinda considering removing them and going for more rubber.
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      02-09-2018, 01:15 PM   #14
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Quote:
Originally Posted by M3 Adjuster View Post
In the photos above , it shows there is a lot of difference between the rounded edge of the Maxxis tire versus the squared off flat edges of the BFG tire.

The BFG contact patch literally goes to the edge of the tire whereas the Maxxis does not because of roundness in the carcass and tire mold.

The R1s In 285/30/18 stack more reliably for storage because they are flatter, and they literally have a smaller diameter which makes fitting them inside the rear of my 1M easier than the 275 Maxxis.

Hoosier seems to be a flatter shape as i recall but nothing like the BFG.
The largest R1 I see is 285/30/18. Which 315 are you running?

EDIT: You must be using the R1 S. Tirerack makes it sounds like this tire will fall apart on long hot day stints. Have you used them in those conditions?

Thanks.

Last edited by ZM2; 02-09-2018 at 01:21 PM..
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      02-09-2018, 05:21 PM   #15
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Quote:
Originally Posted by ZM2 View Post
The largest R1 I see is 285/30/18. Which 315 are you running?

EDIT: You must be using the R1 S. Tirerack makes it sounds like this tire will fall apart on long hot day stints. Have you used them in those conditions?

Thanks.
I went and looked and it only shows R1-S but there has also been a standard G Force R1 in the past.. with it being the winter season.. perhaps a new replacement is coming?
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      02-10-2018, 09:20 PM   #16
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Spent quite a bit of time tonight going thru all the Extreme Summer and Track tire specs.

Couldn't find proper F/R sizing for a set of staggered 19s to work and be worthwhile vs 18".

However, the R888R comes in a 295/30/18. The 295/30/18 would fit, but is still 1.3" shorter diameter than the stock rear and 0.3" shorter than the 265/35/18 front track tire. 1.7" more rubber on each side in the back, but seems like this wouldn't give the ideal F/R handling balance.

The R888R also comes in a 315/30/18. I'm guessing this won't fit in the back, but I've asked Apex if they think it could fit on their 18x10.5 ET40 FL-5 or one of their 18x11 ET44 wheels. That would give a massive 2.4" more rubber on each side in the back and gets the rear diameter closer to where it needs to be (25.5" vs 26.3" stock).

Couldn't find a good 305/30/18, which would be ideal.

Will let you all know what they say.

Last edited by ZM2; 02-10-2018 at 09:30 PM..
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      02-11-2018, 04:41 PM   #17
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Following up, another option is the 305/30/19 RE-71R paired with a 265/35/19 front.

By looking at tire specs and from my non-precise garage measuring, I think this would barely fit and not rub under compression if I could get a 19x10.5" rim with an ET of 48-52.

Sound crazy?

I’ve heard of someone running this tire on the OEM rear wheels, but they were on stock suspension. I’m dropped 3/4”, so the 305/30/19 would definitely rub the fender unless I can push the offset in some.

Last edited by ZM2; 02-11-2018 at 06:13 PM..
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      02-12-2018, 12:08 AM   #18
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Quote:
Originally Posted by M3 Adjuster View Post
I found some photos. The new Tire is the Maxxis RC-1 in 275/35/18 and the worn tire is the BF Goodrich G Force R-1 in 285/30/18.
The tires in that photo can't be an 275/35/18 RC1. Those tires run very wide. I have a set in my garage that that I just double checked and the tread width alone is 10.5 inches. Section width is 11.3 inches.
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      02-13-2018, 07:13 PM   #19
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Circling back on this, looks like 19s are the way to go for a staggered setup. The 285/30/18 and 295/30/18s are just too short compared to stock and front 265 or 275/35/18s.

19s with a 9.5" front and 10.5" rear will allow the tires and sizes below:

R888R- 265/30/19 & 295/30/19 or 305/30/19
RE-71R- 265/35/19 & 305/30/19
R7- 265/35/19 & 295/30/19

Offset on the 10.5" will be key to fit on a lowered car. Supreme Power fit 295/30/19s in the back on 19x10.5 ET45's on a slightly lowered car here: http://f87.bimmerpost.com/forums/sho....php?t=1455216

I'm going to try some test fits this week and will report back.
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      02-14-2018, 08:45 PM   #20
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Adding to this, my race shop (RRT in Dulles, VA) and Supreme Power says you really don't want to run a shorter rear than the front, as it will mess with the TC, even if it's off. Factoring that in leaves the below options:

18s
265/35 Square – RE-71R, R888R, PSC2
275/35 Square – R7 (tight squeeze)

19s
265/30 & 295/30 – R888R, PSC2
255/35 & 305/30 – RE-71R (likely squirrely F/R balance)
265/35 & 295/35 – R7 (doubt the 295 clears)

So, I'll keep my 18s and run RE-71R and R7s on them. And, get a 19" set for staggered R888R's; it adds 0.5"/1.5" to each of the front/rear tires compared to the 18s. Time will tell which setup drives better and is quicker.

Anyone driven the PSC2 compared to these tires?
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      02-15-2018, 10:11 AM   #21
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Another M2 owner suggested 18s in the front and 19s in the rear. I’ll look over those combos this weekend.

I’ll just keep talking to myself until I figure this out for all of us.

Last edited by ZM2; 02-15-2018 at 10:47 AM..
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      02-15-2018, 10:55 AM   #22
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Quote:
Originally Posted by ZM2 View Post

Anyone driven the PSC2 compared to these tires?
Had the PSC2 last season on oem wheels in stock sizes. Went through two front sets over the course of ~12 days. Prior to camber plates the fronts were shot after about 3 days (maybe 12 dry 20 min sessions). Outside corner extreme wear and tearing. With 2.7 camber, coilovers and alignment, the second set of fronts lasted about 5 days, 21 sessions. Rears probably could be used for another day. This is all at instructor pace.

Overall, my take on them is that they had good grip and were easy to manage when they let go. Only issue was the extreme wear. In my opinion, they are very temp sensitive and don't like being over heated and you need to manage them as they warm up otherwise they will tear. Dialing in camber to something like 3.5 could probably address this. I spoke to Will Turner about the issue (He happened to be testing at LRP), and he said his cars run anywhere from 4-5 degrees of camber.

At any rate, I don't have anything to compare the PSC2s, yet. This year I plan to go to dedicated Apex 18x10 wheels running NT01s 275/35 square. So will be interesting to see how this helps.
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