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Michelin Porsche Cup Tires on FD ?

Old 11-22-09, 09:17 AM
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Michelin Porsche Cup Tires on FD ?

Anyone have any experience with Michelin "Porsche Cup" tires ?

What's their "life" like after 120-mins. of use ?

Any experience or thoughts on running a larger diameter rear tire (e.g., 25-in. front and 26-in. rear) ?

Thanks,
:-) neil
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Old 11-23-09, 01:48 AM
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They are a good tire. They will lose the initial super stick after one heat cycle and they will stay good ( about 1.5 seconds per lap off new) for another 6 or 7 heat cycles. They last a long time. I have at least 7 cycles on mine and they're still 40-50% tread.
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Old 11-26-09, 03:29 PM
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Are these any different from the michelin pilot sport cups?
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Old 11-26-09, 11:21 PM
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i'm describing the racing slicks, not sure we're talking about the same tire.
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Old 11-27-09, 12:21 AM
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Old 11-27-09, 12:37 AM
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I'm pretty sure he's talking about the Michelin Slick used in the Porsche Cup. Specifically the take offs that have seen one session of use.
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Old 11-27-09, 12:52 AM
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To clear up some confusion, Neil is asking about the full slick Porsche Cup tires... not the Michelin Pilot Sport Cup R Compounds. Speaking of slicks. I just picked up some Hoosier Koni Challenge slicks that I'm going try out next weekend at Road Atlanta If you are interested in the Hoosiers Neil, I know a couple of places that have a pretty killer deal on these(depending what size you need). Shoot me a PM if you are.

Brent

Edit: Specter328 beat me to it
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Old 11-27-09, 02:01 PM
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I've been told the Grand Am slicks are harder than the R6 because they're used for endurance races, which makes 'em way harder than the A6s...
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Old 11-28-09, 06:29 AM
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I've been using the Koni series tires for the past couple of years. They are treaded radials that are typically shaved down to a "slick" appearance. They will last a season or two if you are just doing driving events but they are not as sticky as newer R6's. They are a good compromise and you can pick them up for about $80 per tire used.

As for the Michelin's, I thought those were only made in Porsche sizes. If you can fit them on your car then go ahead. Keep in mind that they work very well for a couple of heat cycles then they go away fast. If you have the budget to replace them on a regular basis then they are a very fast tire.
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Old 12-01-09, 12:04 PM
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Originally Posted by gkmccready View Post
I've been told the Grand Am slicks are harder than the R6 because they're used for endurance races, which makes 'em way harder than the A6s...
Yes, they are harder but still will be just fine for track days. As far as the A6's go, the hardcore Time Trial guys use them(and they are the fastest tire IMO) but they can't stay out more than a few laps at a time so you better hope you can get a clean lap quick It's not looking good for Hoosier to sponsor TT again though, so I doubt many people will be running A6's every event again as they were literally running them for 1 event only... and at $1000+ a set, it will add up quick!
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Old 12-01-09, 12:16 PM
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A6's are really an autocross tire.

Thing to look out for with race slicks is they are often bigger than their street counterparts, even at similar sizes. I've got some RolexGT Hoosiers, sized 280/640/18, and they are significantly wider and taller than a 285/30/18 Hoosier R6. I've not run them yet, but am concerned about rubbing and even fitment on a 10" rim.

The Michelin sizes I've seen are 660-680 diameter at that width, they really may be too tall for your setup. Best to study the actual sizes closely.
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Old 12-01-09, 01:14 PM
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Originally Posted by ptrhahn View Post
A6's are really an autocross tire.

Thing to look out for with race slicks is they are often bigger than their street counterparts, even at similar sizes. I've got some RolexGT Hoosiers, sized 280/640/18, and they are significantly wider and taller than a 285/30/18 Hoosier R6. I've not run them yet, but am concerned about rubbing and even fitment on a 10" rim.

The Michelin sizes I've seen are 660-680 diameter at that width, they really may be too tall for your setup. Best to study the actual sizes closely.

Michelin Porsche Cup
24/64/18 = Tire Width (mm) 240 mm
Diameter (mm) 643 mm = 25.3"
Sec. Width (mm) 252 mm on 9.5X18


Michelin Sport Cup
265/35ZR18 Tire Width (mm) 265 mm
Diameter (mm) 640 mm = 25.2"
Sec. Width (mm) 276mm on 9.5X18

Michelin Porsche Cup
27/68-18 Tire Width (mm) 270 mm
Diameter (mm) 680 mm = 26.9"
Sec. Width (mm) 270 mm = 10.9" on 9.5X18

Michelin Sport Cup
285/35-18 Tire Width (mm) 285 mm
Diameter (mm) 257 mm = 25.9"
Sec. Width (mm) 289mm on 9.5X18

The rears are 1-inch taller in diameter.
I don't know why Porsche/Micheline recommends running the rear tires taller . . .

PM'd you Brent.

:-) neil
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Old 12-02-09, 03:29 PM
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Few guys are running the throw-offs over here....even over a couple of years, seem to be holding up...no data in the endurance setting you're contemplating though. Guy who could afford to spend 600au new each corner for them each meeting went to Dunlops, as there was a bit more speed there - shorter races than you guys normally run.
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Old 12-03-09, 02:43 PM
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Porsche runs the taller tire in the rear because the shorter tire can't handle the G load produced by a rear engine car on a banked surface. You need the extra sidewall to absorb the shock loads.

-Trent

Originally Posted by M104-AMG View Post
Michelin Porsche Cup
24/64/18 = Tire Width (mm) 240 mm
Diameter (mm) 643 mm = 25.3"
Sec. Width (mm) 252 mm on 9.5X18


Michelin Sport Cup
265/35ZR18 Tire Width (mm) 265 mm
Diameter (mm) 640 mm = 25.2"
Sec. Width (mm) 276mm on 9.5X18

Michelin Porsche Cup
27/68-18 Tire Width (mm) 270 mm
Diameter (mm) 680 mm = 26.9"
Sec. Width (mm) 270 mm = 10.9" on 9.5X18

Michelin Sport Cup
285/35-18 Tire Width (mm) 285 mm
Diameter (mm) 257 mm = 25.9"
Sec. Width (mm) 289mm on 9.5X18

The rears are 1-inch taller in diameter.
I don't know why Porsche/Micheline recommends running the rear tires taller . . .

PM'd you Brent.

:-) neil
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Old 12-06-09, 01:13 PM
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Does anyone know of any more tire sizes in the Mic slick? I have been looking for something closer to a 285/30/18 or a 295/30/18. The rear cup slick listed is about one inch to tall for me. I'm trying to run a matched front and rear setup.
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Old 02-22-10, 11:58 PM
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At the PCA Citrus Feb event at Roebling Road, I ran the Koni Challenge Hoosiers in 275/40R18 on all four corners, and I love them.

However, with an AtomicRx manual rack, the steering effort is considerable, but I'm only running negative (-) 1.2-degrees front camber.

I'm thinking about running negative (-) 2 degrees instead up front, for more grip and easier turn-in.

Does that make sense ?

:-) neil
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Old 02-24-10, 12:34 PM
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Thought I would comment since I have run the michelin porsche cup and the hoosier r6. Michelins will be faster easily, but if they are used vs. new r6 then who knows. Depends on how many heat cycles I guess. I have not driven the koni tires so no comment on that, only heard that they are same compound as r6. Must be something different about them because they run 3 hours on them without changing right, and fairly heavy cars too? Probably more rubber on them.

I have a new set of hoosier r100 slicks waiting to be mounted, that will be my new tire of choice because of the 17 inch sizes and contingency program offered. The cost is higher than the r6 but they should be able to compete with the michelin slick. Longevity of the r100 is still unknown.
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Old 02-24-10, 06:22 PM
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Originally Posted by TrentO View Post
Porsche runs the taller tire in the rear because the shorter tire can't handle the G load produced by a rear engine car on a banked surface. You need the extra sidewall to absorb the shock loads.-Trent
Actually, referring to the use on banking, it's not that specific. All 911-based race cars run very tall rears. It's a lot to do with the 35-65 weight split they run at best, they have to be sprung very stiff at the rear so they run tall sidewalls to try to regain some control in the tread surface.

I wouldn't go running a 680 rear on my FD. That's going to have a major effect on the gearing! The table I use to calculate tyre height effects quickly tells me that at these would be your road speeds in each gear (running a standard box and to 8500rpm.)

1st 47.383
2nd 81.903
3rd 118.645
4th 165.035
5th 204.758

Compared to these road speeds with a 640 rear;

1st 44.596
2nd 77.085
3rd 111.666
4th 155.327
5th 192.713
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Old 04-19-10, 11:14 PM
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The 680mm height tyre has better cushioning effect with a high torque engine (like a drag car) and produces better "power down" out of turns resulting in less wheelspin. Or vice versa!

The more powerful more torquey "Cup S" uses a 710mm height tyre on the rear! I have some and they look like Drag slicks they are so high!

Apparently the 680mm height 270 tyre produces a bigger footprint than a 650mm height 270 and that's another reason why they use them

I am not about to enter into a written argument about it. If you don't believe it just talk to the TOP Porsche teams , the Michelin distributor or go to the Michelin website. Bigger footprint from simliar width tyre sounds stupid at first but its true and explained on the Michelin website much better than I can explain it.

Another advantage of the higher tyre is that they set the car up with less neg camber and this also adds to the footprint.

For FD no advantage with higher tyre unless the engine produces 450ft lbs or more at low to mid range revs somehow.
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Old 04-20-10, 11:45 AM
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I run the Yokohama A005 slicks on my road race FC and my compadre runs them on his FD. Last year I ran the 230/625/17 up front and the 280/650/18 out back. This year I'm going to the 260/640/17 up front. The FD ran that setup last year to good effect. This year he's planning the 280's up front and a 320/650/18 out back.

If you want a short tire, look at the goodyear 16" slicks. You can get a 23.5"x10.5"x16 slick up front and a 25.5"x12" (or14")x16 out back.

-Trent
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Old 04-20-10, 01:24 PM
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Originally Posted by munroman View Post
The 680mm height tyre has better cushioning effect with a high torque engine (like a drag car) and produces better "power down" out of turns resulting in less wheelspin. Or vice versa!

The more powerful more torquey "Cup S" uses a 710mm height tyre on the rear! I have some and they look like Drag slicks they are so high!
Don't forget that most Porches are sprung with crazy high rates to try to keep the suspension from doing stupid things so they end up using the tire to get some spring in the car...
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