Quote:
Originally Posted by AndyW
So, first, I have to say, thx to those who have me advice on the sequence of what to do to get my 135i to be a great streetable track car. I will now apologize because I am disregarding some of that advice... 
Guess I am just one who wants to learn the hard way. Anyhow....got a few track days under my belt, and, to me, it is clearly the RFT stock tires that are my current limitation. I realize the conventional wisdom is to upgrade suspension next (and I actually agree with the logic) but I think I am going to do tires first. For the following reasons:
1. I don't have the 3-4K right now to drop on the setup I really want (and don't want to do the suspension incrementally) and
2. I don't want to trash my RFT's (which are basically brand new)
3. Even if they weren't RFT's, I can now feel the 215 width of the stock front tires is too narrow.
So a second set of wheels with decent streetable track tires seems logical.
Car is a 2012 M-sport. Only mods are brake shims, RBF600 brake fluid, a K&N Filter and an upgrade FMIC. No tune yet(see, I didn't disregard all the good advice! ).
I have read way too many threads on staggered vs square and 17" vs 18" and there are clearly lots of opinions. This is what I believe to be the case:
1. 135 has crappy offsets and a tight front wheel well to properly do a square setup without some mods (up to and including the ECS wider front bumper and fender kit). Or I have to accept a smaller tire width all around. One option has a lot of dollar signs to do correctly (and I like to do things correctly) and the other one seems like a step backwards.
2. Square gives more "neutral" control, staggered has more understeer but better staightline grip during acceleration.
I am leaning toward staying staggered... (This article is pretty convincing), especially since I am still a newer driver and understeer is "safer".
3. 17" and 18" wheels can both come with the same width (and therefore contact patch) but 17" wheels and tires are lower unsprung weigh and typically cost less, which both seem like pretty good positives. Also seems like lots of dedicated track cars go 17".
4. 17" wheel and tire options seem more limited than 18".
I think the minimum I should put on front right now is a 235 (from what I've read 245+ requires camber plates and fender rolling to prevent rubbing and I'm not there yet.)
So, two decisions I need some help with...staggered vs square and 17" vs 18". I've pretty much settled on RE71's as the tire since this will still be a streetable car and I intend to drive to events on the tires I will track with (swap out the night before). I suppose i am willing to do a slight roll of the fenders (the tool is only $50 or so) but really don't want to do major surgery on my car at this time.
Any recommendations welcome! Next year is the suspension mod...I promise... |
I have a BBK so 17" we're out of the equation for me. I have been running Apex staggered setup on track for a few years (R888 235 front 255 rear, no rub) but just decided on the Apex SQUARE setup last week. I put them on 2 days ago and have been testing the new r888r 245/40/18 for rub issues. Yes 40 sidewalls in front... but please note, the new r888R 245/40/18 is only 0.2" taller than the r888 235/40/18 according to Tire Rack dimensions (and the 235s do not rub). The front spring perch clearance is TIGHT (Bilstein PSS10) so I am testing with a 5mm spacer on R Front, no spacer on L Front (see photo). Why 245 and not 235? Try putting power down with 235s in the rear...
Preliminary results:
The Rear 245 is gently rubbing the fender LINER under heavy compression (due to the wheel offset - a 245 will NEVER rub in the REAR using the correct, staggered offset). This is a non-issue for me personally.
So far zero Front rub under compression in a straight line, with or without the spacer. At full lock the 245 with the 5mm spacer (up front) is rubbing the fender liner (thanks to added caster from M3 arms). At 1/2 to full lock AND under minor-moderate compression, the R Front with the 5mm spacer is also rubbing the fender (inner edge, I am NOT rolled). I will write up a full thread as soon as I finish my field work (including track use) in the next couple weeks.
From my years of searching and communication with Apex/Tire Rack/Turner I have found that info is hard to come by regarding square setups for the non-M 135i.