[flybigjet]

Ok guys-- this is complicated, but when isn't it? I posted up on Wheels/Tires but thought I might get a better answer here.

The basics:
2020 M2C:
- M-Performance suspension (lowered)
- Millay Street camber plates (~2.5 degrees?)
-Apex EC-7's
F:19x9.5, ET28 (OEM is 19x9 w/ ET29)
R:19x10.5, ET45. (OEM is 19x10 w/ ET40)
- Tires (100% clearance w/ M-P's conical springs-- but it's TIGHT):
Michelin MP4S 255/35/19 & 275/35/19 (+1 from OEM)
Michelin Cup2 Connect 255/35/29 & 275/35/19 (+1 from OEM)
- Tuned to ~100+ hp/tq from OEM.

The Question:
I've been using Cup2 Connects for HPDE's. I really like them (at least until they start to get greasy at the end of a session), but they're expensive for something that I only get 5-6 track days out of them.

I'm considering the Bridgestone RE-71RS as they're roughly $100 cheaper per tire. However, I understand that there are fitment issues with them on occasion as they're wider and blockier than expected.

I'm reasonably sure that running them in 255/35/19 would hit the wheel shroud (not interested in molding it), so maybe go down to stock size of 245/35/19 in the front and 265/35/19 in the rear?

Pro's? Con's?

I haven't been able to find any "good" height/width numbers for the Cup2 Connects to compare them to the RE-71's-- and it's an expensive mistake if I get rubbing. All I know is that they run "large" for their size.

So, looking for advice from the Collective. Would I notice any real traction/handling difference going back down to 245/265 for HPDE's on the RE-71's? (I've already had traction issues with the Cup2's as I've been running a tune). The front is the issue for the most part. That MPS conical spring is very, very tight-- it works with both sets of my wheels right now, but there's not much more than ~5mm (that's a guess- it might be a little more) clearance between the wheel/sidewall and spring.

A little help? I'm not willing to change ride height, suspension, brakes or wheels-- so I have to make this work with what I have. Worst case it to put more Cup2's on but the Minister of War & Finance is starting to get testy at my consumables cost.

I'm really looking for an "arrive & drive" tire, but not too terribly concerned with wet traction-- most of the HPDE's here in the summer are pretty dry. All I'll be doing with the tire is putting it on at home, driving 1+30 to the track, doing the HPDE, driving home, then replacing it with my street wheels. Basically, I need a tire legal enough to drive on the interstate, but more biased to the track. The 255/275 Cup2's work. The RE-71's come in that size as well, but would probably be too wide? (How do I figure this out?). Or, go down in size to 245/265 to fit the RE-71's IF that would work?

Or, is there something else I should consider? I keep coming back to the Cup2 Connects and the RE-71RS as they both come in sizes that I need. Not sure of any other tire for HPDE that would fit.

TIA!

R.

[dvas]

I don't think this should be a complicated question as RE71s have been a very popular tire on this platform. IMO, they are a much better value than the Cup 2s. I mean, do the math on the offsets/tire widths, but my gut says that you should not have rubbing. If anything, you may need a little more camber. Either way, I wouldn't go down a tire size.

Another good resource is Apex. Give them a call, I'm sure they would help.

For cross reference, on my '17 M2, I've run square 275/35/18 RE71s as well as NT01s on Apex SM-10 18x10 33ET witn ~3.2 camber lowered on Bilsteins with no issues.

[AlpinewhiteM2C]

flybigjet - not RE71RSs but I've ran 255/35/19 Yokohama A052 (relatively same width as the RE71RSs) on the same spec Apex EC7s (19x9.5 28 offseet). I needed to run a 5mm spacer to clear my M Performane suspension with ample room that would make me feel comfortable. If you don't want to run a spacer, another option is to procure the EC7s with a 22mm offset.

The 275/35/19 tires works well with no modifications needed on the EC7 19x10.5 44 offset.

[flybigjet]

Originally Posted by AlpinewhiteM2C

flybigjet - not RE71RSs but I've ran 255/35/19 Yokohama A052 (relatively same width as the RE71RSs) on the same spec Apex EC7s (19x9.5 28 offseet). I needed to run a 5mm spacer to clear my M Performane suspension with ample room that would make me feel comfortable. If you don't want to run a spacer, another option is to procure the EC7s with a 22mm offset.

The 275/35/19 tires works well with no modifications needed on the EC7 19x10.5 44 offset.

DEFINITELY not getting new wheels. A 5mm spacer might help (obviously w/ new longer lug bolts.

The car's in the shop right now getting some minor things done as the warranty expires tomorrow-- when it gets back, I thought I'd take a look at the clearance on that damn conical spring (Why BMW-- WHY???). Then I figured I'd call Tire Rack and see if they have good width numbers for me-- they used to have some really handy charts listing all their tire measurements, but I haven't been able to find them yet.

R.