Does tread width matter?

[hungryhippo]

Dogbone-
Thanks for the tire insight. I will be trying out the R1-S out next. My R7's lasted 4 days then got really slippery on the 5th day. They cycled out before they corded which seems the most common. Did you try lower pressure? Everyone I talked to runs them at much lower pressure than hoosier recommends, like 30 hot. I guess it doesn't really matter since it looks like you've moved on to Pirellis.

[macdude357]

Originally Posted by DrFerry

A Data Point:
https://blog.tirerack.com/blog/lette...me-of-the-time

Thanks for finding that.

What that shows is that if you get a tire that's way too wide for a given rim (a 285 tire should have at least a 10-10.5 in rim), then yes, you are going to get vague steering feedback because the sidewalls are not being supported properly. It's too bad they didn't try a wider rim on the 285.

[BOOF-M3]

@dogbone

[dogbone]

Originally Posted by DrFerry

Did they assemble a clutch set for you specifically with the supercharger in mind? = Nope. I just bout the Spec-R DCT clutch kit off the shelf from Chris.

Interesting. When I told him I had the supercharger, he immediately said that the off-the-shelf clutch kit would burn up due to the extra heat and that they would need to put a specific kit together. Maybe it was because my car is track-only? hmmm As I recall, it didn't cost anymore. I have not pulled the trigger yet. The car was shifting and accelerating quite well at Laguna Seca a week ago. I just have an occasional nagging shift issue that hopefully will be solved by a different DCT pan and suction extender from Slon-Workshop.

Originally Posted by DrFerry

I see you have 11" wheels. Is that 11" square? Nope. I just bought some 11X18 rears and put my OEM 18X9.5 rears on the front axle.

Got it. I was gonna say, I have never seen an 11" on the front at the track on an E9x M3---especially if it was a stock suspension. Everyone is already offended that I put a 10.5" up front.

Originally Posted by DrFerry

Does your car ever see a track? No it doesn't. I did that professionally for almost seven years at this place and so I don't need to do that much anymore. If I feel the need to do that, I just go back down there and beat on a car. Though I must admit the best parts of my day are the drive to and from work - which is on back roads and is kind of like track driving at 7/10ths... - and shall henceforth be known as practice.....

Ok, I'll ask. As I started with in my first response to you, you seem to have quite the technical background with this. May I ask what your job was at these facilities? Don't be shy!


In looking at the tirerack article you linked, I see what they are trying to say, but I'm a road course guy and I believe the overall demands to be different. I think it's safe to say that during a full 20 minute road course session with 6-8 hot laps that you will build up significantly more heat into the tires than a single autocross lap. So while the narrow tire communicates well and feels good for a single, let's assume, 1-minute autocross lap, I'd say that the narrow 245 tire would get crushed with heat from a road course session, and that the 285 in that article would have held up much better by comparison on a road course. Also, in general, road courses don't turn as sharply as autocross courses, so a slight loss in feedback on a wider road course isn't as much of a detriment. Let's look at it this way----the tirerack article was from 2009 and they used a Mustang GT. Let's assume it was a 2009 Mustang GT. That car weighed around 3500 lbs. If you put a 3500lbs car with 245 (most likely not slicks) square tires onto a road course track for 20 minutes and you are a competent driver that can take tires to their grip limit.....I don't think that's gonna go too well 6 laps in....and how are those 245's gonna look after 5 sessions of a typical HPDE day? I'm not sure I'd want to drive home on those....

[dogbone]

Originally Posted by hungryhippo

Dogbone-
Thanks for the tire insight. I will be trying out the R1-S out next. My R7's lasted 4 days then got really slippery on the 5th day. They cycled out before they corded which seems the most common. Did you try lower pressure? Everyone I talked to runs them at much lower pressure than hoosier recommends, like 30 hot. I guess it doesn't really matter since it looks like you've moved on to Pirellis.

Interesting. 30psi hot is a full 10psi lower than Hoosier recommends.......that's just frustrating. And I'm not saying I don't believe you. All I'm saying is that I specifically called Hoosier and told them all the specs on my car---weight, power, aero, diff, and the type of use (time attack style--one warm up, 2 hot laps, one cool down and off the track), etc. They specifically told me to run at 33psi cold/40 hot. Did I get bad advice from the vendor? I don't know. The guy I spoke with was very knowledgable. I was not speaking with an intern. Anyway, running a full 10psi lower hot is so far from their recommendation, it's.....frustrating.

When possible, I do my best to find the proper way of running things from vendors. Usually I get pretty good advice. As I've said before, I don't come to motorsport with a deep well of knowledge, so I try to give myself the best chance for success by asking lots of questions from reputable places.

[dogbone]

Originally Posted by DrFerry

The circuit performance of the 245 would depend on a lot of things and what type of tire is in question. Not the least of which would be roll stiffness, center of gravity, track width, dynamic camber gain and dynamic toe. Now let me ask you a question. Don't be shy. What does the opening statement of the linked article say about the Mustang GT capabilities? See screen shot.

ummm---are you alluding to the fact that Mustang might not have the correct supporting parts to really deal with the 285 size correctly?

Originally Posted by DrFerry

Now here's something to think about, why are tank tracks oriented in the longitudinal (north/south) direction? Why might this be so?

I don't know the answer for the tank tracks. I don't know how those things work.

[dogbone]

Originally Posted by DrFerry

I Wanna' Go Fast(er)

https://www.michelinmotorsport.com/Tyres/Circuit

Buy them here:

https://www.jacksonmotorsportsgroup...._64&sizes=true

Some catalogs with tech info attached below. See pages 5 and 6 of the last file attached.

Thanks for the links.

For purchasing Michelins, there's an interesting dealer about 30 minutes south of Los Angeles called Subesports. They offer a 10% discount on all their products if you buy a $100 annual membership with them. They keep Michelin slicks in stock and getting 10% discount and not having to deal with shipping (if you're in LA) is pretty nice!

[dparm]

Originally Posted by dogbone

Thanks for the links.

For purchasing Michelins, there's an interesting dealer about 30 minutes south of Los Angeles called Subesports. They offer a 10% discount on all their products if you buy a $100 annual membership with them. They keep Michelin slicks in stock and getting 10% discount and not having to deal with shipping (if you're in LA) is pretty nice!

There's a place near Road America that sells slick take-offs -- typically used for a few laps to qualify and then removed. They're dirt cheap even if I count the gas it takes to drive there and back.

The only downside is that the availability of various sizes/brands is all over the place, so you just have to keep checking and jump on the first set you find.

[135]

Originally Posted by dogbone

I've been to all the tracks in California. I would consider my home track to be Buttonwillow 13CW.

I've never run a new set of TD's once the car was gutted and caged and had full aero at Buttonwillow, so unfortunately I can't give the TDs a fair lap time there.

Also, I have progressed quite a bit as a driver in the last few years. I've been tracking for 6 years. The first 4 years, I use MDM traction control. I have been running for about 2 years DSC-off. So let's use lap times since I was running DSC-off. And now the car is fully setup for the track with cage, gutting, aero, diff, AP, JRZ, supercharger, etc. so lots of stuff has been changing. But I think I can answer most of your questions.

First, I'll compare TD, R6 and A7.

TD - we've been told they're not making TD anymore. I see you're in Australia. Can you still get them? Anyway, as my first "fast" tires, I loved the TD's. The braking grip was amazing. The cornering grip was very good. Where these tires would fall short is once you went past the grip limit. They did NOT like sliding, and they would grind and chatter and vibrate desperately trying to get the grip back. TD's also had a funky characteristic where they DID NOT like to do a lot of hot laps in a row. They preferred one lap hot, one lap off, and repeat. You could DESTROY them in one session if you ran them for 30 minutes straight hammering all hot laps. The rubber would chunk and you'd be unhappy. They heated up very easily in one warm up lap. And if I ran them square, I could get 4 decent days, plus one not-grippy day on them.

R6 - I wasn't a big fan of R6. Believe it or not, the R6 was a slower tire than TD at Buttonwillow. My friend and I both confirmed this. The R6 did not brake as well as TD. But the driving characteristic of the tire was more elegant than TD. When an R6 went past the grip limit, it was a smooth experience. It would lose grip and slide smooth, and then you could get the car back smoothly. The R6 didn't mind multiple hot laps in a row. The longevity of R6 was not great. 10-12 sessions and they corded. They didn't take much work to warm them up.

A7 - *sigh* Hoosier. Interesting tires. Hoosier wants the tires to be 40 psi hot---start at 33 psi. I called them. A7 is a pretty fast tire. Needs absolutely no warm up at all. You look at them and they're already warm enough to go hot right away. But they would get greasy after two hot laps in a row. The third hot lap and the car was sliding all over the place. Very solid braking feel. Good in corners and acceleration. They also slide smoothly like R6. But they have a short life. Mine corded after 8 (short--remember only 2 laps) heat cycles....I don't think I ran them quite as hard as they could be run. I'm a better driver now, but I'm not running them again---too finicky.

I'm going to briefly talk about one or two more tires:

BFG R1S - love this tire. In my opinion, it is the fastest and best value DOT tire short of slicks. Very good braking. Good in the corners. Slides well. Can run a full 30 minutes of hot laps without any issues. Faster than TD, R6, as fast as A7. Lasts 14-16 heat cycles before first tire shows cording. But remember, this is not just 2 laps and get off the track. This could be full 20 minute sessions. Sadly, they raised the price to be the same as R7. They used to be $200 cheaper. These tires need more warm up than any of the previous tires. I say give them two laps on the first run of the day. Later in the day, one lap is enough.

Pirelli DH - phew. Amazing. Once you drive them, you will not want other tires. They hold the ground like crazy. I have 4 sets of rims. All 4 sets have DH on them right now. Need I say more? I find the DH to be 2-3 seconds faster than R1S when they're fairly fresh.

My lap times: Disclaimer: I am not a pro driver. I am not Mr. Automatic lap-after-lap. I'm an amateur/hobbyist driver that has learned as much as I can in 6 years. My lap times have gotten decent over the years, but there is still more time to be had. So, these times do not necessarily reflect the maximum ability of the tires. You asked about lap times and I'm giving you the info as honestly as I can, but these times are NOT the result of some scientific testing----air temps, track conditions, driver skill, car setup, etc are all variables that are different from day to day in these results.

-Buttonwillow 13CW - 1:47.2 (Pirelli DH) (new) (on this lap, the car auto-shifted into 6th gear…..this was probably a 1:46.9 lap……dang)
-Buttonwillow 13CW - 1:48.0 (Yokohama A005) (new) (these tires can do 1:47's. Car had shifting issues.)
-Buttonwillow 13CW - 1:49.0 (R1S) (new) (I had a 1:48.xx on R1S in a time attack but had to stop on the front straight right before the finish line due to another car on fire)
-Buttonwillow 13CW - 1:49.3 (Michelin S9L) (new)
-Buttonwillow 13CW - 1:49.5 (A7) (new) (I believe these tires can go faster than this.)
I do not have a TD time with the car in the same modded state as these times. I would guess I would have done a 1:50-1:51 on fresh TD.

-Laguna Seca - 1:34.3 (Yokohama A005) (new)
-Laguna Seca - 1:35.3 (Pirelli DH scrubs and braking conservatively. I did a long post about this a couple days ago in my build thread. Scrub DH could have gone faster than new Yoko if I braked more aggressively. I showed the AIM chart.)
-Laguna Seca - 1:36.2 (R1S) (new)

-Chuckwalla CW - 1:53.6 (Pirelli DH) (scrubs)
-Chuckwalla CW - 1:54.9 (Yokohama A005) (scrubs)
-Chuckwalla CW - 1:56.0 (R1S) (scrubs)

-Auto Club - 1:43.5 (Pirelli DH) (scrubs)
-Auto Club - 1:44.9 (Yokohama A005 scrubs)
-Auto Club - 1:46.6 (TD)

-Sonoma Raceway - 1:47.0 (R1S) (new)
(I've never driven Sonoma with slicks. Slicks would be at least 2-3 seconds faster.)

-Thunderhill 3-mile w/Bypass: 1:54.7 (R1S) (scrubs)
(I've never driven Thunderhill with slicks. Slicks would be at least 2-3 seconds faster. I've only driven this config three times.....I don't get up to Thunderhill much...I could stand to learn the track quite a bit more.)

-Big Willow - 1:27.5 (R1S) (scrubs)
(I've never driven Big Willow with slicks. I want to soon. it's so hard on tires that you don't really want to bring good tires there. I'm not sure what the slicks advantage would be. Weird track.)

Excellent review!!! I really appreciate all the information.


The TD/Z221 is still available here. We also have access to the Yokohama A050, which is a direct competitor to the TD/Z221, with almost identical lap times. According to the Yokohama website, the A050 is only available in Japan and Australia, although, a new A052 was recently released and available in the USA but it's a slower tyre than the A050 and probably equivalent to a Michelin PSC/PSC2.

There is a relatively new Nankang AR-1 R-comp, which one might not think much of, given the brand and its predecessor, but it's surprisingly a great tyre, being only 0.27s slower on a 60s lap than a TD/Z221 C70 (Soft), while being less than half the price! Not to mention, they can take multiple consecutive hot laps and produce consistent times through the day, and day after day, although they can take some time to get up to temp, which means the first session or two can be wasted getting pressures right.
This information is not entirely useful for you, given your progression to slicks, but hopefully somewhat useful for others starting out and looking for an inexpensive option.


My next tyre was going to be the A7 (the P-car forums seem to love this tyre) but after reading your thoughts, it makes me hesitant.

The BFG R1S seems to be a great all-round option and as good as it gets without going to a full slick. But those extra 2-3 seconds on the Pirelli !!!

How many heat cycles do you get out of the Pirelli DH and how long are those sessions?

What's the falloff in times once the Pirelli DH and R1S are no longer fresh, i.e. second track day and beyond?

[slicer]

Dogbone - thanks for the awesome post.

Question - why have you not tried the hoosier R7? My understanding is the A7 is more of an autocross oriented tire that doesn't need to be warmed up. I would think the R7 would be more suitable for your use and would last longer.

[dogbone]

Originally Posted by slicer

Dogbone - thanks for the awesome post.

Question - why have you not tried the hoosier R7? My understanding is the A7 is more of an autocross oriented tire that doesn't need to be warmed up. I would think the R7 would be more suitable for your use and would last longer.

When looking at the criteria of lap times, heat cycles and price, I think the BFG R1S is a better value. R1S puts down better lap times (TD was faster than R6 and R1S is faster than TD). You get more heat cycles out of R1S. R6 might get 10-12. R1S get me 14-16. R1S drive quite nicely and don't mind a bit of sliding. You can do 30 minutes of hot laps on R1S just fine. Looking at current pricing at tirerack.com, a square set of 285/30/18 R1S is $1406. A square set of 295/30/18 R7 is $1586, so a set of R1S is $180 cheaper right now. And it's worth noting that the 285 R1S is wider than 295 R7.

I guess I'm just not a big Hoosier guy. The R6 was ok. It was elegant but not super fast and it wore out quickly and it's at the top end of price for a non-slick. My friend, who was very familiar with R6 also ran R7. It wasn't much faster and didn't last any longer. I ran A7 because I wanted the grippiest thing I could find and people spoke very highly of A7. Remember, I do time attack-style stuff. Two or three hot laps and get off the track, so A7 should fall right into that.

For the criteria that matter to me, the R1S beats the R7 in every category.

[slicer]

Originally Posted by dogbone

When looking at the criteria of lap times, heat cycles and price, I think the BFG R1S is a better value. R1S puts down better lap times (TD was faster than R6 and R1S is faster than TD). You get more heat cycles out of R1S. R6 might get 10-12. R1S get me 14-16. R1S drive quite nicely and don't mind a bit of sliding. You can do 30 minutes of hot laps on R1S just fine. Looking at current pricing at tirerack.com, a square set of 285/30/18 R1S is $1406. A square set of 295/30/18 R7 is $1586, so a set of R1S is $180 cheaper right now. And it's worth noting that the 285 R1S is wider than 295 R7.

I guess I'm just not a big Hoosier guy. The R6 was ok. It was elegant but not super fast and it wore out quickly and it's at the top end of price for a non-slick. My friend, who was very familiar with R6 also ran R7. It wasn't much faster and didn't last any longer. I ran A7 because I wanted the grippiest thing I could find and people spoke very highly of A7. Remember, I do time attack-style stuff. Two or three hot laps and get off the track, so A7 should fall right into that.

For the criteria that matter to me, the R1S beats the R7 in every category.

Cool. I'll try the R1S next!

[Richbot]

In general, the R7 is faster than the R6 and more durable used properly. Tehy run wider than the sames size R6, in general, also. One does not simply bolt on any new tire and get to optimum, and R7 setup is a bit different than R6 (Some cars it needs more camber, R6 had a more rounded shoulder, they went more square on R7 for instance). You should try it too. The BFG's are very good no doubt. I'd agree they're the best "DOT slick" on the market right now on the speed/value quotient. They seem to wear really well for their speed. But, I think there are a lot of SCCA National Championships Runoffs results that tend to argue against the BFG being the fastest DOT tire on a ground pounder like ours. Hoosier contingency awards are way better, but the wheel to wheel racers do tend to converge on what is faster.

The 295 Hoosier has a wider section width and narrower tread width. And it's nearly half an inch taller, which means it's still a bigger tire overall than the 285 R1S.

When you're talking about these two tires though, you really cannot go wrong.

[dogbone]

Originally Posted by Richbot

In general, the R7 is faster than the R6 and more durable used properly. Tehy run wider than the sames size R6, in general, also. One does not simply bolt on any new tire and get to optimum, and R7 setup is a bit different than R6 (Some cars it needs more camber, R6 had a more rounded shoulder, they went more square on R7 for instance). You should try it too. The BFG's are very good no doubt. I'd agree they're the best "DOT slick" on the market right now on the speed/value quotient. They seem to wear really well for their speed. But, I think there are a lot of SCCA National Championships Runoffs results that tend to argue against the BFG being the fastest DOT tire on a ground pounder like ours. Hoosier contingency awards are way better, but the wheel to wheel racers do tend to converge on what is faster.

The 295 Hoosier has a wider section width and narrower tread width. And it's nearly half an inch taller, which means it's still a bigger tire overall than the 285 R1S.

When you're talking about these two tires though, you really cannot go wrong.

I always value your input Richbot! (I just gave you props in another posting.) Perhaps I'll give the R7 a shot someday.

However, regarding tire widths, tirerack disagrees with you on tread width. The tread width of 285 R1S is wider than 295 A7. Here's what tirerack says: the tread width of the 285 R1S is 11.3" (I just went out to my garage and hand measured a scrub unmounted R1S at 11.4"), and they list Hoosier A7 at 10.8", and the R7 (which I have never seen in person) is 10.7". Tirerack says the section width is .2 wider on Hoosier, but I'm telling ya, when you have them side by side, you don't even need a ruler to see it. I have had 285/30/18 R1S sitting on the floor right next to Hoosier A7 295/30/18 in my garage. You can see it with the naked eye. I know it sounds crazy, but the R1S is just a fat, blocky, crazy-ass barely "DOT" fricking tire hahahaha

I just hand measured the 285 R1S against a 305 Pirelli DH I have here too unmounted. Their tread widths are within 1/16" of each other......how crazy is that?

[dogbone]

Originally Posted by 135

How many heat cycles do you get out of the Pirelli DH and how long are those sessions?

What's the falloff in times once the Pirelli DH and R1S are no longer fresh, i.e. second track day and beyond?

When the weather is cool and I'm trying to run fast lap times, I typically don't run long sessions. The engine just cannot go for more than 2-3 hot laps when "going for it". And staying out on fresh nice tires and just burning them up for no reason seems like a terrible idea. I've bought one set of Pirellis new. The rest have been scrubs. I've run the new Pirelli about 10 heat cycles so far and they're still going strong. The scrubs I buy go 10-15 heat cycles of this style of running. The 305's take some work to cord. The wider rubber simply resists wear better---no surprises. I usually don't cord them. At some point, they just really do not grip very well, and I pull them off. At least when it's cool out and I try to go fast, I pull them off when they slide around. When it's hot, I'll usually leave them on longer since I'm not worried as much about lap times.

I found the first 5-6 short heat cycles on the new Pirellis to be awesome. After that, they were very nice, but not like new. The first hot lap on the new Pirelli was a special experience. It took two warm up laps to scrub the brand new Pirellis in.

R1S feel really good for the first 10 heat cycles. From 11-16 they fall off but are still very fun to drive. I usually cord one by 16 heat cycles in. I'll toss that one and over time assemble scrub sets and get 5-6 more cycles out of them. They're not very fast, but they are fun.

I believe the weight of the car affects these experiences to some extent. The Trinity Autosport E92 M3 is 400 lbs lighter than my car. Joe claims that he can get 23 heat cycles out of a set of R1S. Interesting.

[Richbot]

Originally Posted by dogbone

I always value your input Richbot! (I just gave you props in another posting.) Perhaps I'll give the R7 a shot someday.

However, regarding tire widths, tirerack disagrees with you on tread width. The tread width of 285 R1S is wider than 295 A7. Here's what tirerack says: the tread width of the 285 R1S is 11.3" (I just went out to my garage and hand measured a scrub unmounted R1S at 11.4"), and they list Hoosier A7 at 10.8", and the R7 (which I have never seen in person) is 10.7". Tirerack says the section width is .2 wider on Hoosier, but I'm telling ya, when you have them side by side, you don't even need a ruler to see it. I have had 285/30/18 R1S sitting on the floor right next to Hoosier A7 295/30/18 in my garage. You can see it with the naked eye. I know it sounds crazy, but the R1S is just a fat, blocky, crazy-ass barely "DOT" fricking tire hahahaha

I just hand measured the 285 R1S against a 305 Pirelli DH I have here too unmounted. Their tread widths are within 1/16" of each other......how crazy is that?

I've seen that tire I know it's yuuuuge. They're like that all the way up and down the range too. ultra-square, almost cantilevered, extremely not-hellaflush approved

But tire diameter matters a lot too. A "bigger" tire will give you more grip in more situations all things being equal, even if it's a bit narrower. So it's worth a test at least. Scuse me while I continue to try to spend your money for you It's also 1lb heavier according to TR! When you measure in lb of tire/dollar, the Hoosier almost breaks even!

I'm always going to be a Hoosier (now, Continental, sorta) booster though. Their support for grassroots motorsport in this country is second to none, so, grain of salt and all that

[135]

Thanks dogbone and Richbot.

How many HCs would a set of Pirelli DH scrubs have done? 10 or more? If so, it sounds like you could get 25 short 3-hot-lap HCs out of the Pirelli DH.
Are you still able to run the same times on the new (now 10 HC old) Pirelli DH? Otherwise, how many seconds slower are they now? I'm guessing they're still faster than DH scrubs.

And it looks like the R1S gets 20 HCs, i.e. 10 great HCs + 5 good HCs + 5 scrub HCs.
Were the R1S HCs also 3-hot-lap sessions or were you running 20-30 min (10/15/20 lap?) sessions on them?
Again, are you still able to run the same times on the R1S through its first 10 HCs? Otherwise, how many seconds slower do they get during this first 10 HCs and especially after in the next 5-10 HCs (since that's how you'd determine the value/speed proposition if them).

Interesting - my unlightened 135i weighs about the same as your track-prepped SC'd M3. I haven't gone down the stripped, roll-caged and aero path yet. 2850 lbs (1295kg) would be achievable with my car but that would extremely expensive. A race-prepped 3000 lbs (1360kg) shouldn't be too difficult and bearably expensive.

[kawstik]

Originally Posted by dogbone

I just hand measured the 285 R1S against a 305 Pirelli DH I have here too unmounted. Their tread widths are within 1/16" of each other......how crazy is that?

That's wild.

[dogbone]

Originally Posted by 135

How many HCs would a set of Pirelli DH scrubs have done? 10 or more? If so, it sounds like you could get 25 short 3-hot-lap HCs out of the Pirelli DH.

Scrubs can be unpredictable. I tossed a set yesterday after just a few runs because they drove like garbage. Low grip, bad braking and the car vibrated on them. The next set of scrubs was fantastic by comparison. In a "normal" scrub, I'd say we can run them 12-15 het cycles. The first 5-6 are nice. 7-10 grip is lower but still decent. 11-15 is not grippy.

Originally Posted by 135

Are you still able to run the same times on the new (now 10 HC old) Pirelli DH? Otherwise, how many seconds slower are they now? I'm guessing they're still faster than DH scrubs.

The first 5 sessions very nice on the new ones. 6-8 were pretty darn decent. 9-11 today were fairly good. 11 runs in, I think the scrubs will start catching up now. Was cooking the "new" ones at Willow Springs today. If you ever want to put some hate on a tire, take it to Willow Springs.

Originally Posted by 135

And it looks like the R1S gets 20 HCs, i.e. 10 great HCs + 5 good HCs + 5 scrub HCs.
Were the R1S HCs also 3-hot-lap sessions or were you running 20-30 min (10/15/20 lap?) sessions on them?
Again, are you still able to run the same times on the R1S through its first 10 HCs? Otherwise, how many seconds slower do they get during this first 10 HCs and especially after in the next 5-10 HCs (since that's how you'd determine the value/speed proposition if them).

Many were 3-hot-lap runs, but I would also run R1S longer sometimes because I'm not as careful with them. The fastest complete lap I ever ran on an R1S was on it's 8th heat cycle. I make the distinction that it was complete because on another R1S set I was running a faster lap in an earlier heat cycle, but the session was Red flagged before I could cross the finish line. Anyway, I think the R1S is good for the first 8-10 heat cycles. After 10 heat cycles, the drop off is.....geez.....I never looked at it scientifically, but I'd say a couple seconds off.

Originally Posted by 135

Interesting - my unlightened 135i weighs about the same as your track-prepped SC'd M3. I haven't gone down the stripped, roll-caged and aero path yet. 2850 lbs (1295kg) would be achievable with my car but that would extremely expensive. A race-prepped 3000 lbs (1360kg) shouldn't be too difficult and bearably expensive.

It's expensive to make an E9x M3 light. I drive an E9x M3 on track because I like the platform. When I see my car sitting there quietly in the paddock, it makes me smile. If I wanted to go out and really drop the hammer on everyone and do it within a reasonable budget, I'd start with a Miata and go to crazytown with it. In the RWD category, the Miatas are taking over time attack. Although, at Global Time Attack at Buttonwillow today, a Honda "Civic" did a 1:37.308. That's .2 faster than the Billy Johnson record done in the NSX. I saw the "Civic" yesterday and talked with the owner----it has 807whp (conservatively) and is 2300 lbs and has huge aero. He said he would run 315 A7 on the front wheels for the time attack. Amazing build.

[roastbeef]

I'm guilty of having a secret fantasy of a track miata. Maybe I can tell Elyse it's her track car? Lol

[Richbot]

Miatas are no picnic to make go fast around a racetrack reliably too. The wheelbase and pckaging constraints (tire, cooling frontal area, jellybean aero is horrendous)

[rymerc]

Originally Posted by dogbone

a Honda "Civic" did a 1:37.308. That's .2 faster than the Billy Johnson record done in the NSX. I saw the "Civic" yesterday and talked with the owner----it has 807whp (conservatively) and is 2300 lbs and has huge aero. He said he would run 315 A7 on the front wheels for the time attack. Amazing build.

If I had a set of tires for each <$10k civic running GT3-times at mid ohio, I'd be set for the season