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#1062124 - 06/02/19 12:18 AM Michelin Pilot Sport 4S Tires  
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This is not Monte related per say but thought I’d post it in case someone was wondering if the Michelin Pilot Sport 4S tires (PS4S) were as good as Michelin claims. Just bought a set of them for my daily driver G8 GT (with 245/40/19s) replacing a set of the older Pilot Super Sport tires (PSS) and I can say they are every bit as good as the hype over them.

The razor sharp handling of the PS4S is every bit as good (can’t say with certainty they’re better) and the ride quality is a drastic improvement over the PSS tires. I was seriously considering dropping down to aftermarket 18s on the G8 because the ride was so harsh with the PSS tires. It’s not like the PS4S tires magically fill in the potholes and road imperfections but they certainly effectively dampen them. Road joints around here are pretty bad in spots and with the PSS tires the repeated “ka-thunk” and jarring impact was terrible. Now the car practically floats over them with these PS4S tires. I probably wouldn’t believe there could be this big a difference in ride quality and not lose anything in the handling department if I hadn’t actually experienced it for myself.

I’ve finally decided on the wheels for my Monte and plan on ordering them pretty soon. I was having to go with 18s out back to get the right sized tire to fill the fender openings but was going to go with 17s on the front to help with ride quality. Now, I’m pretty sure I’ll end up going with 18s up front with PS4S tires. They’re a bit pricey, but I’m convinced now they’re worth every penny!

#1062149 - 06/03/19 08:48 PM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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Hi BadSS,

I'll try to answer this on the premise that when two tires are compared on a given car and one is judged to be better than the other, then the same parity will hold on any other car. I say that because my experience with the PSS is not on a G-body.

My experience with the PSS is extremely favorable. My "other" car isn't known for its handling, yet the PSSs completely transformed the car's handling, in conjunction with a switch to a much stiffer rear sway bar.

Specifically about the PSS vs. the PS4S: all the reviews I've read have favored PS4S. But ride comfort doesn't seem to be a factor that was rated as being significantly different. May I suggest that any time a new tire is substituted for an old one of the same kind, that the new one will feel smoother and sound quieter than the old one. This is because the old tire has usually seen a lot of wear, so the outer 1/4" to 3/8" of tread thickness (of usually IIR rubber, with a high loss factor) has been stripped away. With this considerable amount of highly-dampened rubber removed, the old tire will ride noticeably more roughly and more loudly.

So my suspicion about your experience of the PS4S riding more smoothly than the PSS is that it's not inherent in the design, but just an artifact of having full tread thickness on a new tire.

HTH,
MAP


Last edited by MAP; 06/03/19 08:49 PM.
#1062157 - 06/04/19 01:52 AM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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BadSS and MAP - I'd like to address the technical differences in tire age, as opposed to wear. May or may not be the case here but I wanted to restate that an important consideration if holding on to older tires is the change in their properties and performance due to continuing cure in storage, regardless of use or wear.

A very complex system. Sulfur (polysulfidic compounds) are used to crosslink polymers with carbon black reinforcement. (Silica reinforced tires for improved fuel efficiency use silane couplers; a similar issue). A balance of accelerators are added to increase cure rate and reduce manufacturing time while retarders are used to keep premature initiation at a minimum and thereby achieve uniform and predictable cures. (I had an analogy here about sex, but can't remember it???). The tire is placed in a press, Superheated steam heats from both the metal mold side (tread) and from the inside (bladder against the inner-liner). Typically, a passenger tire might be subjected to 350 psi, 350 deg F heat and take 15 minutes. Imagine what the times on enormous off the road and mining tires would be, and the different heat history on the surfaces vs several inches deeper into the rubber? As the tire heats through, the cure initiates. Curing occurs as an "S curve", slow at first while heating, then very fast once hot but the last bit of curing takes much longer due to limitations on diffusion, etc. Tires are therefore intentionally under-cured. Leaving them in to get to "full cure" (tha is all sulphur consumed/complexed) would take way too long to be economical but would also initiate "reversion" where unfavorable reactions reduce the favorable curing linkages.

So, what do we buy? A tire that really performs consistently and well, but which has an abundance of unreacted cure agent. It continues to react but at reasonable operating temperatures very very, very slowly. So perhaps we are running at 85-90% of theoretically complete cure. What happens to the remaining sulfur?

(Geek alert: As a rule of thumb a chemical reaction doubles in speed with every 10 deg C increase in temperature. Cure temperatures approach 15 decades difference over ambient, so that is 2 exp 15, or 2**15 slower reaction than when the tire sees in the curing press. What's that number?).

Result - our tractive and flexible tire gets harder, less compliant, has less grip and runs noisier with time. Even when stored in the garage.You almost always feel improvement when switching to a new tire. We have age restrictions on helmets which I don't fully understand. Running on old tires however is just not fun. Or even wise. Do NOT take those near-mint OE tires that came with the car out on anything but a show event; they don't perform as well as they once did and they could be experiencing other age related degradation. (Back to that analogy...)

Back to the PSS vs PS4S vs other maximum performance summer tires; these are all hard rides, and can't be driven at near freezing road conditions. BadSS - Thanks for the very interesting comments on the two. How old and how worn were the PSS? I considered the PSS in particular (PS4S has very few sizes), thinking of the 255/40-ZR18 and 285/35-ZR18). As my ride is already harsh and I am trying to soften it, I went with an all season radial (Goodyear Eagle F1 asymmetric). But then I have a retiree discount.....

Thanks again,
Gordon

#1062175 - 06/04/19 08:03 PM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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Hi Akron,

What a terrific post! I take it you're a tire or a chemical engineer?

Thank you for that great explanation. I've had to specify sulphur-free IIR for some applications due to corrosion with nearby electronics...

So, the residual cross-linking increases modulus and reduces loss factor. Good for wear, but not good for traction! So just as you say, this, in combination with the shedding of rubber over the life of the tire, means a new tire will ride softer and quieter than the old one other things being equal.

Back to the PSS/PS4s: my experience with the PSS was nothing short of phenomenal. I imagine the PS4S, based on the reviews I've read, is even better.

Best,
MAP

#1062192 - 06/05/19 03:10 AM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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Thanks for all the interesting information provided on this post. All other things remaining equal, there is no doubt new tires with full tread will provide a better ride than hardened worn out tires.

To give some background information, I bought the car new in 2009 and it came with Potenza RE050A tires. I had about 25,000 miles on them when I bought the first replacements which were the Super Sports. Now, those RE050s were 7 years old (rubber had hardened) and were worn out. There was never a “wow moment” when I replaced the old RE050s with the new Super Sports. The ride quality with the PSSs was SLIGHTLY better than the old tires, which was expected considering the aged (hard) and worn out RE050s. However, the PSSs made the car feel like it was on rails and straight line traction was restored.

With me now driving the car daily, the Super Sports were about 3 years old with a little over 15,000 miles on them, down to a little less than ½ tread. A pot hole killed the two right side tires – one pinched enough to lose air, the other enough to put a knot on it. I had been looking for 18” wheels for a couple weeks prior because I had never been that happy with the ride quality of the car, but I tried to justify the trade off with how well it handled. Messing up those tires forced me to get something that I could get quickly and I WAS NOT going back with two old and two new-old-stock PSSs. I remember reading something somewhere that everything including ride quality had been improved with the new PS4Ss. So, I made a quick google check on my phone, found the TireRack review below, and hastily ordered the tires before they closed for the day (shipped the following morning).

https://www.tirerack.com/tires/tests/testDisplay.jsp?ttid=223

“The Michelin Pilot Sport 4S received the highest subjective score from our testers in every criterion, but was particularly favored for its handling. The weight and build-up of steering effort felt perfectly natural, and response to inputs was millimeter-precise without being overly sensitive. Ride quality and relatively low noise were also strong points for the Pilot Sport 4S, with a firm, composed ride that reduced impacts to a single event and no intrusive tones over the varied surfaces of our route.”

After the “wow moment” with the PS4Ss I thought I’d share how happy I was with them and let those running plus sized wheel/tires know that they could have their cake and eat it too. After reading the responses here, I thought I’d look around to see if there was anyone else that was impressed as I was with the difference in ride quality with the new PS4Ss. Here’s what a few thought about them compared to P Zeros, which looking at the TireRack testing above, I would have thought there should be little difference between the two.

https://rennlist.com/forums/991/1057885-pirelli-p-zero-to-michelin-pilot-sport-4s.html

OP - “I'm shocked how much of a difference it makes to the ride quality (biggest difference) and sound (a bit quieter).” “It has smoothed out the problem areas as I would expect a DSC module might have done.”

Another poster - “mpss to mp4s is more of a sideways move imho - better wet grip supple ride no better in dry really”

Another poster – “I just now found this thread as I took delivery just last week on my new Targa 4 GTS. My 5th 911, but my first one with the Michelins (PS4S). All my other 911s came with the P Zeros. I decided to research this topic on Rennlist because I was astonished at how much better the ride quality was on the Michelins. Quieter, more comfortable and smoother all the way around.”

Another poster – “After my 981 Boxster S (which curiously had Pirellis) the ride quality of the Turbo was a real disappointment. Fitting these Michelins (PS4S) has made it a different car altogether in respect of ride quality."

Anyway, I know my comparison as well as the others that I quoted above are not scientific and could easily be discounted for a number of reasons. However, I'm a pretty critical person, usually better at finding fault than praise (oh no, I just realized I've turned into my dad!!) but I'm lovin' these tires and the overall car experience again. Saved myself a lot of money sticking with the 19s too.

#1062196 - 06/05/19 02:24 PM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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Gordon's tire aging post above backs up what those of us that race on UHP tires have figured out. Brand New 200 TW tires have the best ride quality but grip isn't there yet. After about 2-3 events depending on the # of runs and # of heat cycles they really start to grip well. This is probably a combination of the tread blocks wearing down some and the rubber curing. As they age and the # of heat cycles increase, they really start to have a harsher ride but the grip level stays the same (once you get heat into them). The RE71s and Rivals will have great grip right down to the wear indicator blocks and even further but the ride quality deteriorates. For me anyway, once they get to the wear indicators they start to get pretty slick once again and I find myself lusting over new rubber.


Lance
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#1062198 - 06/05/19 03:18 PM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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"Tire shaving four new tires often improves performance in competition, track use, or autocross racing. New treads have more give, or squirm, due to greater tread depth and any small elements on the tire meant to improve wet traction. This give decreases performance in dry racing conditions" - TireAmerica. Often HP / race tires come with slightly shallower tread, too
Gordon

#1062199 - 06/05/19 05:14 PM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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Some may balk at the thought of shaving tread off brand new tires...racers on the other hand understand it completely. laugh


Lance
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#1062200 - 06/05/19 08:00 PM Re: Michelin Pilot Sport 4S Tires [Re: MAP]  
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Originally Posted by MAP
Hi Akron,

What a terrific post! I take it you're a tire or a chemical engineer?

Thank you for that great explanation. I've had to specify sulphur-free IIR for some applications due to corrosion with nearby electronics...

So, the residual cross-linking increases modulus and reduces loss factor. Good for wear, but not good for traction! So just as you say, this, in combination with the shedding of rubber over the life of the tire, means a new tire will ride softer and quieter than the old one other things being equal.

Back to the PSS/PS4s: my experience with the PSS was nothing short of phenomenal. I imagine the PS4S, based on the reviews I've read, is even better.

Best,
MAP


MAP or Akron, you guys ever deal with peroxide cured rubber for Hi-temp use?


86 SS 6.0L LQ4, TBSS GEN IV intake, 92mm TB, 30lb injectors, Summit Stage 3 NA Cam, Stainless long tube headers, Stainless 3in exhaust, Microsquirt ECU, FABbot AR5 5-speed, Torsen LSD, QA1 Lvl 3 Suspension Kit, UMI Front & Rear Braces. Check out my build blog on Summit Racing's OnAll Cylinders https://www.onallcylinders.com/author/travis-jones/
#1062202 - 06/06/19 01:12 AM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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PK - MAP is using Butyl (IIR) which has several complex and aggressive cure chemistries as there are not a lot of cure sites available.
Latex gloves and medical stuff uses peroxide cures, which give better chemical and thermal resistance over sulphur, and a clean product.
Choice of polymer in many of these applications is EPDM rubber.
Not a compounder but what are you thinking?


BadSS - loved your comments. I am strongly considering a switch to one of those once I get all the other bugs worked out. Pulled the dash out today for a complete dash/instrument swap. Keep us updated on how it behaves in high/low temp, rain, etc.

Gordon

#1062226 - 06/06/19 05:22 PM Re: Michelin Pilot Sport 4S Tires [Re: AkronAero]  
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Originally Posted by AkronAero
PK - MAP is using Butyl (IIR) which has several complex and aggressive cure chemistries as there are not a lot of cure sites available.
Latex gloves and medical stuff uses peroxide cures, which give better chemical and thermal resistance over sulphur, and a clean product.
Choice of polymer in many of these applications is EPDM rubber.
Not a compounder but what are you thinking?


BadSS - loved your comments. I am strongly considering a switch to one of those once I get all the other bugs worked out. Pulled the dash out today for a complete dash/instrument swap. Keep us updated on how it behaves in high/low temp, rain, etc.

Gordon


I was just going to make the joke about how badly peroxide cured rubber smells. if you have handled it, you'd know!


86 SS 6.0L LQ4, TBSS GEN IV intake, 92mm TB, 30lb injectors, Summit Stage 3 NA Cam, Stainless long tube headers, Stainless 3in exhaust, Microsquirt ECU, FABbot AR5 5-speed, Torsen LSD, QA1 Lvl 3 Suspension Kit, UMI Front & Rear Braces. Check out my build blog on Summit Racing's OnAll Cylinders https://www.onallcylinders.com/author/travis-jones/
#1062232 - 06/06/19 06:18 PM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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I worked at a gasket shop in college, and it seemed to take days for your hands to look and feel normal after processing a big batch of PC rubber...


Sometimes you just need a bigger hammer...

'85 MC with budget 5.3L swap, TH350 with stock 2.14 rear end
It ain't much off the line, but it's nice on the highway
#1062234 - 06/06/19 08:38 PM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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Hahaha. All rubber chemicals are pretty unique, and aggressive. When I worked on the Gulf Coast, we could tell in the evening/weekend where someone worked by their smell. The gift that keeps on giving. Regs and care for (understanding of) environment have come a long way.

#1062243 - 06/07/19 10:19 PM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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Hi Folks,

Akron: IIR is king of loss factor, and that's why I use it instead of SBR, NBR, or EPDM. We need the high tan(delta) in loudspeaker surrounds to control cone breakup.

Thanks,
MAP

PS: I remain curious about your profession?

#1062244 - 06/07/19 10:59 PM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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Map - you were right of course... I think you always are. Comical/Chemical Engineer. 35 Years with Goodyear (part of it in a JV with Michelin in France). Career divided between managing polymer manufacturing, tire materials R&D and last third in global marketing (polymers), IP and strategic planning. Dabbled a bit on the tire side (Detroit and F1 projects were fun). Retired at 56 when the Tire division absorbed our very profitable Chemical division to hide their continued losses. Lost the joy. Became a Sr Fellow at the University of Akron Research Foundation (15 yrs pro bono) but I started a few small companies (one a beer company, but we drank up all the profits), and an Angel investment network. Glad to share more with anyone, anytime. Current Monte efforts have me hustling to swap in the Just Dashes dash and speedhut gauges before the Nationals In Piqua. I have a true"parts car" - that is, every part has been upgraded for performance (except the radio). I'll get around to posting a thread if I every decide where to host the pics. You? Glad to know you are in acoustics. Doing auto/air dynamics too?

Exxon made demos sets of three different colored rubber balls which were sent to schools. One was a typical (natural) rubber for the teacher with expected bounce, one a "super ball" formulation for a young woman guaranteed to hit the ceiling on the second story, and one IIR/butyl where the "men" could show off their power against the "girls" I have never seen any who could get the IIR ball to bounce more than an inch off the floor. hahaha. A really dead polymer.

Gordon

#1062254 - 06/08/19 09:56 PM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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Now that's a profession! I'm very impressed, Gordon/Akron! Thanks for sharing your technical expertise and being part of the discussion...

BadSS - I don't want to sidetrack your thread. One effect you've had is definitely to convince me to switch to the MPS4S once my current MPSSs wear-out (which isn't far in the future.) With a UTQG rating of 300, this is the maximum rate of wear I can tolerate for a street car. One thing I might say is that the wider/stiffer the tire, the more critical it is to keep the average orientation of the tire perpendicular to the pavement, and to minimize the variation of that orientation with your statistical profile of steering and suspension inputs. The goal is symmetrical treadwear, and a minimum variation of that wear across the transverse face of the tread. (I see Lance is posting here, and he goes the extra step of periodically re-mounting his directional tires to ride on the opposite side of the car to improve this symmetry, but I doubt whether everyone reading here would go through that trouble.) BadSS, I don't know your front end geometry or alignment specifications, but if it's anywhere close to stock, these conditions will not be met. For expensive tires like the MPSS or the MPS4S, I think this becomes an important consideration, at least to maximize treadlife, if not just to maximize performance.

Best,
MAP

Last edited by MAP; 06/08/19 10:07 PM.
#1062283 - 06/09/19 10:24 PM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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There's no sidetracking here and if it were, I certainly wouldn't mind - especially considering the information being shared.

After getting a new set of tires, the first thing I do is to see how they act under hard braking (dry and wet). I can’t say for sure if dry braking is any better than the PPS’s but the car’s braking ability has always impressed me. It rained for a couple days around here and I had to drive in a pretty substantial downpour. I hit the brakes hard and fast at 50mph (no one else around) and it pulled on down quickly with full control. Again, I can’t say if it was any better than the PSS’s (when new), but I think there’s less chance of me running up under someone and more likely someone would run up under me in a “typical” emergency braking situation.

Strut mounts in these Australian G8s, Camaros, and GTOs are typically going out around the 40-50,000 mile mark and that pothole took out the mount on the same side as the tires also. Going to replace them with some “Polyelast” mounts from SuperPro. Info from them claim they’re “made from a new high-grade, low-deflection synthetic polymer hard enough to limit deflection, yet compliant enough to absorb almost all NVH.”
Feedback from all the forums seem to back up their claims saying they really do work a lot better than the weak stock rubber mounts without adding all the unwanted NVH from the urethane mounts. I’m mainly going with them because I’m driving the car a lot more now and don’t want to have to replace the stock type rubber mounts anytime soon.

On a side note, I’m a stereo nut and have always had really nice stereo systems in the house and car – at least for the money I put into them. Nothing super high-end, just good solid, clean, accurate sound. There’s a lot that goes into designing a good speaker and the surround material is one of those things that has to be right.

Gordon, I’ve installed a number of systems in Monte Carlos (and other cars) on the side for many years. So if you ever decide to do something with the stereo, let me know.

MAP, I have a good friend that set the first alignment on the car when I got the PSS tires and he said he rarely sets things to stock specs. However, he’s retired now so I’ll have to get someone else to align the car once I put in the new struts and mounts. I’ll catch up with him when all the parts come in to see if he remembers where he set the alignment before or if there’s someone he could recommend – I have trust issues with people working on my cars (lol).

#1062284 - 06/10/19 12:15 AM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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Kevin - I'll watch your posts and consider PS4S next year if they offer more sizes, otherwise may consider PSS, but must iron out a few things first. I assume you/others would recommend having fronts and rears set up with similar performance tires? That is not just upgrade rears for traction?

Yes on help with stereo. Running a very loud 383 with large cam and AFRs. Engine dyno was 535HP/487FtLb running 89 Oct at 9.9:1 compression. Feeding Hooker 304 SS headers and 3" 304 SS true duals with open Borla mufflers. Exhaust was bolted to the frame with slip joints bolting pipes together (for the track). These of course let lots of sound/gas leak directly under the car. Not my interest now so put lap band clamps on pipes and connected to frame with silicone bushing mounts this past week. Much quieter but still quite loud. Car is completely lined with Fat Mat 80 ml Rattletrap. (MAP - I know the IIR/butyl would have been better). Wife won't ride in the car and I have considered reducing the cam at some point in the future (maybe to get more vac if I go to EFI). Always wanted a good sound system but not useful if I can't hear over the exhaust... hahaha. I installed 6x9 kappas (probably 65 watts RMS, or maybe more. I need to look up power range) in the rear 8 years ago when I did the restomod. Only got around to installing the oversized kappa 3.5" two ways (35 watts RMS) when I did the dash swap last week, Haven't tried the radio yet with the new speakers, and know I will need to upgrade to get into more useful range of the speakers. Thinking about getting a receiver (HD and CD, I don't need all the software apps) - these typ carry 14 watts RMS. Thinking too of an amp like Kappa 4 (4 channel at 100 watts RMS, not sure I want a bass box in the rear?). I can do speakers in kick panels or doors panels too if I need to get away from the dash speakers eventually. Thoughts please on any or all of this?

MAP - will fire off a PM shortly.

Gordon

#1062316 - 06/11/19 03:28 AM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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Rear tires would depend on what you're planning on doing with the car. If I were road racing the car, I'd want the same size tires on all four corners. The same for a daily driver so I could rotate the tires. However, if you're driving the car normally (for the most part) and you need traction, I've actually cruised around with slicks aired up to around 22lbs. So, I've run different tires front and rear and having a hard time deciding if I want to drop the coin on another set of rear wheels, or just put the ET Street Radials on the car and look straight ahead (pun intended - lol).

Stereo - First thing I’d recommend running the exhaust over the axle and straight out the back bumper. I daily drove a 406 in the SS back in the day that cranked 614HP in the cell and I thoroughly enjoyed the air conditioning (windows rolled up) and stereo system. No smell in the car and not that loud once run out the rear (compared to the turn downs under the car).

For head units, best bang for the buck for a sound quality system, is the Pioneer DEH-80PRS. Built with higher quality internal components it has a 105db s/n ratio on the CD. Another huge plus is capability to run an active 3-way system (separate amps for tweeters, midrange/mid-bass, and woofer/subwoofer, independent R/L equalizer, auto tune, and time alignment. It has Bluetooth, dual rear USB ports, and a few other perks, but it’s not loaded with many frills. You can read up on it below. This is what I’d go with if CD sound quality was the primary goal. They usually run around $250-$275 from reputable sites.
https://www.pioneerelectronics.com/PUSA/Car/CD-Receivers/DEH-80PRS

Pioneer has another one that I’m guessing would be a better fit for you, the DEH-X8800BHS. Built-in Bluetooth, Front and Rear USB Ports, HD Tuner, wireless audio streaming, and can add SiriusXM. Signal to Noise ratio on the CD is OK at 94db and the big plus is that it also has time alignment and the capability to run an active 3-way. They run between $160 and $180 from reputable sites.
https://www.pioneerelectronics.com/PUSA/Car/CD-Receivers/DEH-X8800BHS

Not saying you can’t get really good sound in a car without going active (did it for years), but once you do, you’ll realize what all you’ve been missing. I could never go back to "normal".

That said, for now (Stage 1), I’d recommend whichever of the two head units above fits your needs the best and a good 4-channel amp to get what you have powered up. Stage 2 would be to add another amp to power a/the sub(s). Would suggest mounting a pair of high excursion 12s under the rear deck (there’s enough room in a coupe to do this) and moving the 6x9s behind the rear side panels (use speaker cloth to hide them). You can use the standard crossover mode and time alignment to “pull” the sound up front.

I cut holes up high in my door panels back in 1986 and moved the power window switches down where the door locks are. If I hadn’t already cut up the door card, I’d probably go with kick panels. The weakest link in the G-body cars is the lack of decent sized speakers up front. In a true hi-fi system, you want as much sound as you can get coming from up front. Next step up for you would be kick panels with a high quality 6” woofer and tweeter. You could go with DIY raw drivers like Vifa, ScanSpeak, SB Acoustics, or Seas (to name a few) and save enough money compared to the better boxed speakers to buy an amp and go active.

Anyway, just throwing some things out there. Budget will dictate how mild or wild you would want to go.

PM me if you want some recommendations on amps.

#1062369 - 06/13/19 01:14 AM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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Kevin - considered the DEH-X8800BHS, but didn't know it had active 3-way (learning more) etc. Not obvious. Love the DEH-80PRS too. I'll post thoughts and questions on a PM. Thanks for the offer. This opens some options I hadn't thought of. Thanks,
Gordon

#1062370 - 06/13/19 02:06 AM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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AkronAero Online content
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Kevin - you are over your PM limit. Can you clear space or send me your email via PM?
Gordon

#1062393 - 06/13/19 11:53 PM Re: Michelin Pilot Sport 4S Tires [Re: AkronAero]  
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BadSS Offline
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Originally Posted by AkronAero
Kevin - you are over your PM limit. Can you clear space or send me your email via PM?
Gordon
Never noticed that counter before - lol Cleared out and PM sent!

#1062412 - 06/16/19 06:30 AM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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MAP Online content
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Hi Folks,

There's so much temptation to get into auxiliary topics! My car speaker designs are in millions of vehicles. I'll just say it's almost impossible to get over about 50dB useful s/n in a car without going deaf. Look instead at things like low symmetrical, credible sound-staging, low distortion, and wide bandwidth.

Back to the tires: BadSS, you should get fairly even wear across the tread face on the rear axle, but the front will give you trouble with the stock suspension geometry, even with very stiff suspension bushings. The problem is mainly camber variation with suspension motion and steering inputs. The car's tendency to roll should also be reduced from stock.

For handling purposes, I would never use a narrower tire on the front than the rear if I could avoid it. The stock design simply has too much weight riding on the front axle to warrant the classical "skinny/fat" hotrod stance. In fact, if traction weren't an issue on the rear, the car would probably handle best with wider tires in the front than the rear. The underlying problem is that the car does a fairly good weight impersonation of an FWD vehicle, notwithstanding the design is RWD.

Best,
MAP

#1062419 - 06/16/19 10:49 PM Re: Michelin Pilot Sport 4S Tires [Re: MAP]  
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MAP Online content
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Hi Folks,

That last post got messed-up when I edited it. The third sentence should read, "Look instead at things like symmetrical, credible sound-staging, low distortion, and wide bandwidth." About FWD weight distribution: for the stock design, with its original weak handling and anemic acceleration, a front-heavy RWD car is still OK. But when we up performance by several notches to extract everything the tires can really give us, it becomes a significant problem. The stock front-end suspension will also wear-down the tire shoulders too rapidly: we need to get the front roll center location under control. Stock, it flails all over the place as the suspension moves.

Best,
MAP

Last edited by MAP; 06/16/19 10:49 PM.
#1062445 - 06/19/19 07:02 PM Re: Michelin Pilot Sport 4S Tires [Re: BadSS]  
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MAP Online content
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Hi Folks again,

Another post in a stream of consciousness: more on the flailing of the stock front roll center. In reality, that location is strongly influenced by the compliance of the tires and to a lesser extent, the suspension bushings. I'm using the concept of roll center in this case, based on a fictitious condition where there are no compliances and only simple, friction-free rotations. In other words, it's where software (wrongly and simplistically) tells us the roll center is.

The compliances have the effect of stabilizing that flailing to a significant extent. It also tends to make its height closer to the pavement. Recognizing this, I believe the GM engineers took every liberty they could with the very soft tires of that time to mask the deficiencies of their front suspension geometry, because those deficiencies, after all, reduced weight and cost, and made more space in the engine compartment. Soft tires, other things being equal, were also cheaper and helped NVH. With that limited range of thinking - that thinking being the softest possible ride at the lowest possible cost - how could they possibly lose?

But now we find ourselves in 2019 among enthusiasts who are using tires that by the standards of around 1975 when the A/G body was designed, hardly even existed in racing circles. Today's tires are far, far stiffer, and for this reason, un-mask the deficiencies of the original suspension, allowing much of the theoretical flailing of the front roll center to return with ruthless efficiency. And this is made even worse with the use of stiff suspension bushings. And worse still, by using wide tires, camber changes - a consequence of roll center flailing - compound shoulder wear.

So even though the MPSS vs. MPS4S question has nothing to do with the suspension per se, I think it's a reasonable stretch to assume that anyone using these tires on an MCSS will use the widest that will fit, and on this basis, plus the fact that these tires are expensive and we don't want their lives unduly cut short by exaggerated shoulder wear, it becomes important to improve the front suspension. And, of course, handling improves with reduced understeer and a bigger tire traction circle.

Hope that helps?

Best,
MAP

PS: A while back I spoke about how we can get the tire to "self-camber" by using a rim that's wider than indicated for the tire section width. Wish I could remember where that thread(s?) was(were?) I even posted simple sketches of how this worked.

Last edited by MAP; 06/19/19 07:18 PM.
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