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Discussion Starter #1
Seriously considering going to track only R compound tires for my M5. Anybody out there done it? What brand and sizes all around? I have 18" rims with Michelin PS2 all around now.
 

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Toyo RA1 or Dunlop SP Sport Race work well. If you are a novice or even intermediate, stick to street tires until you are sure of your abilities, then switch to R-comp or slicks.
 

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What Redshift said. I would not run R compound tires unless you are expert/instructor level with many track hours under your belt. Yes you will be faster and yes you will be more confident in your abilities along with the car but...

Once those R's lose adhesion you better be skilled like Shuey to save it otherwise you will be in a world of hurt along with your M.

I have seen this first hand at the track from M3, Vettes and S2000. They look great and fast right up to the point of crashing.

-Jeff
 

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Nolift911 said:
What Redshift said. I would not run R compound tires unless you are expert/instructor level with many track hours under your belt. Yes you will be faster and yes you will be more confident in your abilities along with the car but...

Once those R's lose adhesion you better be skilled like Shuey to save it otherwise you will be in a world of hurt along with your M.

I have seen this first hand at the track from M3, Vettes and S2000. They look great and fast right up to the point of crashing.

-Jeff
Just as importantly, good tires can mask bad driving. You will learn more on street tires that slip and slide than R compound tires with better grip. For the guys that have crashed on R compound tires, I would suggest some instructor error is involved. Students shouldn't be running on the ragged edge (at least not with me in the car!!!! :nono: ). If the students are soloing, that is different, especially late in the day when the "red mist" sets in and there is no instructor to rein them in...... :cheers:
Regards,
Jerry
 

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Discussion Starter #5
Thanks for the warnings! I do have a lot of track time and run in advanced groups and solo. However, I AM out there for fun and NOT shunting. What about a compromise like a Michelin Pilot Sport Cup? I don't think they make it in stock wheel sizes though.
 

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MPSC is less of a compromise than you think, only because it gives no feedback (i.e. squealing) like other tires do. It may have a predictable traction limit, so if you are advanced enough to feel it, the MPSC should work okay for you. You might need to consider adding 2 rear OEM wheels up front to do something like this.
 

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Redshift said:
MPSC is less of a compromise than you think, only because it gives no feedback (i.e. squealing) like other tires do. It may have a predictable traction limit, so if you are advanced enough to feel it, the MPSC should work okay for you. You might need to consider adding 2 rear OEM wheels up front to do something like this.
Great point! I was in an S4 at Summit Point with an instructor and he was running R compound. He was "showing" me the track and then we went into the carousel and he began showing me the agricultural side of the infield areas, quite a ride and no harm done but...

I'll never forget the eerieness of it on the R compounds - no noise, no drama, just like the hand of god scooted the car off to the infield and we spun. We came to a rest and looked at each other like wtf? Well that is R compound.

I have a number of events under my belt and solo's also but I would not wear R's unless it was a track only car that I would not care if it got bent. With R's it is not if but when you off the car and hopefully it is all grass and no hard walls.

Personally R's are meant for racing; period. You will become so much more of a better driver on streets anyway. I like the fact that I can pass some R outfitted cars on the track in my 911 with my KD's. Granted they are at the limit where street tires go but they do make a fuss when you reach the limit and I know it is time to cool it. Plus I get to drive the car home nice and straight hiha

-Jeff
 

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I've switched from PSCs to RA1s. Didn't think the PSCs lasted as many heat cycles as i'd anticipated and they are very sensitive to tire pressure -- but fast when they're new and you've got them at 32-34 PSI hot.

RA1s are very predictable and not as fast -- can't say for sure about life yet.

Advantage of track tires is they get so greasy when hot -- particularly important if you track during hot weather -- other advantage is you're not buring thru your street tires
 

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Jeff, your experience is the main reason I went back to R-compounds instead of slicks on my Z06. I had a student in the car with me late last year and the rear end came around quite abruptly with no noise or drama, and scared the bejeezus out of my student (not me - I just corrected and kept going). He screamed "Why didn't the tires make any noise! That was wild!" and I explained that very sticky tires tend to make less noise at the limit (and over the limit) than street tires. The grip was incredible with those Hoosiers but it's not quite as good a learning experience for the students, and for a car that I need to drive home in, I decided to switch back to something that makes noise :)
 

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I highly recommend the Falken Azenis tires for track driving. They last a long time, are cheap, STICK great (for a street tire), and howl progressively to let you know you're getting close to the edge. Unfortunately the largest size they come in is 245/45/17, so they'll only work with track rims of coure, plus you'd be giving up some width at the rear on the M5. I used this size on my 540 & was happy with them, and also on my E30 before switching to RA-1's.
 

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For a street tire, check into Toyo T1-S. I use that for my street tires on all the cars plus also for wet track driving. It's great all around.
 

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Discussion Starter #12

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that's a great piece of information on the RA1s, particularly that they're not directional in the dry -- very useful on the M5 to swap tires left to right on back-back track days

no excuses now, next project is front camber
 

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I have gone through three or four sets of RA1's on my E34 M5. Great idiot proof tire and not heat-cycle sensitive. They do howl and give you some warning but break away gradually anyway. I flip them once the shoulders are gone and actually can get 12+ days out of them. Can't beat that. I bought some of the P Zero Corsas from Tire Rack. After one day I have concluded a bit grippier than RA1, especially for being new but I think they come with less tread. However, I can't flip them due to construction and they almost overheated on a 45 degree day (almost chunked but I guess my session ended just in time)!! I had ran them on the street for a few days to break them and RA1's have never done this with the same treatment.

RA1's are not the fastest but are the best DE tire I have used. I did a couple of years on RE71s before switching to an R compound. My friend made the mistake of lending me his. Oh my. There was NO way I was going back.
 

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It looks like I need to try the RA1s. I've run Kuhmo Victoracers for quite a few events. They don't squeal but do make as much growling noise as the PS2s and seem progressive to me. They don't last very long but my only problem with them is there is a limited number of laps when they are at their best. The first laps and last laps are always fun with greasy tires. I do agree that a beginner would have a harder time finding the limits safely but I've gotten very comfortable with them and found it difficult to find the edge when back on the PS2s.
 

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Discussion Starter #17
According to the article, optimum operating temps are between 160 and 220.
I have not taken temps on my PS2 after a session so I don't know what I'm at with those. Have any of you taken readings to see if you are in the range?
If not, perhaps the tire won't improve over PS2 as much?
Also, neg 2 to 3 camber is recommended. What is stock and did you guys change the camber at all? My suspension has been lowered so my camber is more negative (?) than stock but I will have the shop measure it when I go in next. When you say "flip" you mean swap rims right?
Overall sounds like the RA1 is a great tire. Oh, one more question! Am I better off starting out with an unshaved tire to see how it progresses or go right to 6/32? If it's my first time on an R maybe it will ease me into the feel?
 

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M5ROKIT said:
According to the article, optimum operating temps are between 160 and 220.
I have not taken temps on my PS2 after a session so I don't know what I'm at with those. Have any of you taken readings to see if you are in the range?
If not, perhaps the tire won't improve over PS2 as much?
Also, neg 2 to 3 camber is recommended. What is stock and did you guys change the camber at all? My suspension has been lowered so my camber is more negative (?) than stock but I will have the shop measure it when I go in next. When you say "flip" you mean swap rims right?
Overall sounds like the RA1 is a great tire. Oh, one more question! Am I better off starting out with an unshaved tire to see how it progresses or go right to 6/32? If it's my first time on an R maybe it will ease me into the feel?
When I say flip, I mean remove the tire and flip it on the rim. I would also start with unshaved. They just get a bit squirmy when hot in the first few events. You just slow down a little if they get that hot.
 

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i think you'll notice a difference between the RA1s and any street tire when the tires and track are hot

i've seen air temp in the tire (from Smartire) up to 220F on a 100F afternoon. Haven't measured tread temp on a hot day as there's not much i can do about it without adjustable camber (which i'll hopefully get done in March)

with the Dinan III suspension i'm running 1 degree in front and 2 rear -- need 3 in front (i think Kevin is running 2 degrees in front on his E34)

i think the RA1s are a bit faster if the track is cool and significantly faster and less greasy when really hot even with less than optimum front camber

if you're only going to run a few events, street tires are okay, but if you run a lot RA1s become cost-effective
 

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Just FYI, my car runs perfectly balanced on track and wears tires very evenly with -2.2 deg. front camber and -1.8 deg. rear with equal sized tires all around, a GC suspension, and Dinan rear bar. I set the front shocks at medium and the swaybar to maximum oversteer OR neutral. I had the car corner weighted for 51/49 weight balance.
 
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