Quote:
Originally Posted by ayao
I'm finding that I want more grip than AD08s offer on the track. I'm not sure if that's because I'm overdriving, or if I'm progressing in skills, or something else. So I'm kicking around the idea of R-comps.
Currently on staggered 18" M3 OEMs (245/40, 265/40) and the only R-comps that fit these are Trofeo R's. They seem finicky with camber and pressure. I don't like finicky. Other options include:
-making the stock 19" 359s the track wheels which would allow R888s and MPSCs
-going 275/35/18 square on 18x10 et25s
I definitely like the idea of improved wear. And a bunch of R-comps are made in the 275 size. How much do you think going square will change the balance of the car? I feel like it's pretty balanced and relatively easy to throttle steer through turns ... do you think going square will make it too prone to oversteer? That's my major concern at the moment.
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As far as wanting more grip... makes sense... the AD08s are ok.. but definitely not great.. street tires like the HankooK RS-3 and the Direzza II are better performers..
As far as entry level R tires.. the Nitto NT-01, Maxxis RC-1, and Toyo R888 are all tires that have fantastic wear, reasonable price and a step up in grip over the street tires. While not being fast as the TOP DOG "R" compounds, they will wear well and be a very good value. Tires like the Michelin Pilot Sport Cup, Hoosier, BFG R1, and Dunlop Maxx Race are definitely significantly more expensive - save those for when you are competing.. if that day occurs..)
The 18" OEM M3 wheels you have are really only suitable for street duty or winter tire use. Smaller than stock wheel width IIRC (8.5 front and 9.5 rear?) along with stagger is no bueno.
So.. if on a budget.. (sorta).. you could go with R tires on the stock wheels (saving you $1200 in wheel expense) and go with something like a 255 up front and a 275 or 285 rear would work... but you are still left with more expensive track tires (19s vs 18s) in the short run plus less rubber than you can ultimately run if you were to go with new wheels like the APEX and the car will also still understeer.
Ever since the E36 M3... BMW has been putting smaller tires up front than the rear.. It could be for looks.. but more likely... it's to create understeer, which makes the car safer. However.. I am absolutely in favor of a square setup on most BMWs.... (with the 1M and perhaps Z4 as the possible) exceptions to the rule.) On the E30M3.. E36 M3... and the E46 M3... a square setup is usually preferred in racing..
With the 1M.. my personal preference is to go as BIG as possible.. on all corners... And if you want to give up a little bit of rear grip for wear then go square.
As far as changing the balance of the car.... well.... if you LOVE the current balance.. then try square.. you might find you like it MORE! It seems that you are concerned with oversteer... when this chassis actually has too much UNDERSTEER designed into it. Yes.. it *can* and does oversteeer easily with provocation from your right front (by either lifting or putting it to the floor).
With more rear tire.. the car does come off the corner better.. but when it comes time to brake and turn... then the car understeers at the limit. Therefore.. rather than putting something like an itty bitty 245 up front... the 275s up front on a square setup give you more grip up front so you can turn.. Add camber plates and to a square setup and you will find that the car actually is MUCH more neutral overall. It will be as close as possible to naturally not oversteering OR understeering AND you get the better wear. And don't forget... you can still create oversteer... *any* time you want... and this won't change at all.
For those that are entering TIMED events... racing.. time trials.. or if you just have to have the fastest time... If that's the case.. then go as big up front as possible and go as big on the rear as possible, and try and keep a 20-30 mm difference front to rear. While I havent tested this myself with lap times.. (and i will try to do so sometime soon) I have heard this is the *fastest* setup...
if you want the fastest setup that will fit under the wheel wells... then go with what Harold at HP Autosport recommends... I believe you indicated 9.5/10.5 with a staggered tire size.