|
|
|
KEEP M3POST ALIVE BY DOING YOUR TIRERACK SHOPPING FROM THIS BANNER LINK! |
Post Reply |
|
Thread Tools | Search this Thread |
10-05-2009, 08:45 AM | #45 |
Brigadier General
2510
Rep 4,381
Posts |
I rang Michelin tech support again and:
The bloke confirmed that there will be a slight increase in grip as the tyres wear from new peaking at around half worn. He confirmed that as you approach the wear bars the tread wear reduces due to the tread not heating up as well. He said that from about half worn the grip plateaus until the wear bars. He said that in normal usuage (12k miles) he didn't think heat cycling would play a part in changing grip (making the tyres last say > 50000 miles might well introduce tyre compound hardening through heat cycling). It seemed to me that increased tread life at near the wear bars should equate to less grip and I pressed him on this a couple of times but he was adament that there would be no significant decrease in grip from the peak at about half worn to the wear bars. Don't know if this makes it any clearer. |
Appreciate
0
|
10-05-2009, 09:14 AM | #46 | |
Major General
812
Rep 7,888
Posts |
Quote:
|
|
Appreciate
0
|
10-05-2009, 10:49 AM | #47 | |
Major General
374
Rep 8,033
Posts |
Quote:
__________________
|
|
Appreciate
0
|
10-05-2009, 11:19 PM | #48 | |
Lieutenant General
609
Rep 10,407
Posts |
Quote:
__________________
E92 M3 | Space Gray on Fox Red | M-DCT | CF Roof | RAC RG63 Wheels | Brembo 380mm BBK | | Vorsteiner Ti Exhaust | Matte Black Grilles/Side Gills/Rear Emblem/Mirrors | | Alekshop Back up Camera | GP Thunders | BMW Aluminum Pedals | Elite Angels | | XPEL Full Front Wrap | Hardwired V1 | Interior Xenon Light Kit | |
|
Appreciate
0
|
10-05-2009, 11:31 PM | #49 |
Lieutenant General
609
Rep 10,407
Posts |
Sounds interesting and promising but not entirely consistent. Can you really call it a "peak" in grip at about mid life when after that point the grip is maintained constant on a plateau? I would not call that "peak" per se, just a plateau. It also does sounds quite fishy that tread wear decreases but grip stays constant (again after about mid life). Lastly when does the plateau end does it simply hit a vertical "brick wall" right at the wear bar or is it right at cording? It must come down at some point and even get below the grip when just broken in. If it drops in the way he described then it must come down sharply, like going over a cliff.
__________________
E92 M3 | Space Gray on Fox Red | M-DCT | CF Roof | RAC RG63 Wheels | Brembo 380mm BBK | | Vorsteiner Ti Exhaust | Matte Black Grilles/Side Gills/Rear Emblem/Mirrors | | Alekshop Back up Camera | GP Thunders | BMW Aluminum Pedals | Elite Angels | | XPEL Full Front Wrap | Hardwired V1 | Interior Xenon Light Kit | |
Appreciate
0
|
10-05-2009, 11:35 PM | #50 | |
Lieutenant General
609
Rep 10,407
Posts |
Quote:
__________________
E92 M3 | Space Gray on Fox Red | M-DCT | CF Roof | RAC RG63 Wheels | Brembo 380mm BBK | | Vorsteiner Ti Exhaust | Matte Black Grilles/Side Gills/Rear Emblem/Mirrors | | Alekshop Back up Camera | GP Thunders | BMW Aluminum Pedals | Elite Angels | | XPEL Full Front Wrap | Hardwired V1 | Interior Xenon Light Kit | |
|
Appreciate
0
|
10-06-2009, 02:52 AM | #51 | |
Brigadier General
2510
Rep 4,381
Posts |
Quote:
There does seem a logical conflict between admitting that as you approach the wear bars there is a reduction in the tyre wear rate but no change in grip...suggesting that its a function of the tyres reduced ability to heat up I suppose is plausible , but not totally convincing. I guess I could be a victim of "selective memory"...by coincidence the tyres on my M3s could have been wearing out as we entered into winter and the reduced traction was a function of reduced temperatures rather than an overall reduction in tyre grip. As I noted before, a few years ago I had already discussed this apparent phenomenon with Michelin so convinced I was of its repeatability...now I'm begining to doubt myself. As far as how grip changes as you pass the wear bars, we didn't really get into that. Here the weather in winter is such that running your tyres below the wear bars is not sensible and will get you into serious trouble if stopped by the police...each tyre below 1.6mm will get you 3 points on your licence - 12 points = lost licence. |
|
Appreciate
0
|
10-06-2009, 07:43 AM | #52 |
Major General
812
Rep 7,888
Posts |
Not at all as the PS2's have been worn down by use and have had numerous heat cycles vs the shaved tires that only had one heat cycle.That is a big difference in the way that the the tire was used.
|
Appreciate
0
|
10-06-2009, 07:50 AM | #53 |
Major General
812
Rep 7,888
Posts |
Our fastest tire setup was always the new shaved to 2/32's(minimum tread depth by the rules) that we used for qualifying or a short race where the tires would still be quick and not be corded before the end of the race.If started on 4/32 with a few heat cycles on it became quicker as the tread disapeared with our fastest laps usually at race end ,but remember this is a single session with no further heat cycling.
Last edited by Gearhead999s; 10-06-2009 at 08:41 AM.. |
Appreciate
0
|
10-06-2009, 08:16 AM | #54 | |
Major General
374
Rep 8,033
Posts |
Quote:
Regardless, that specific scenario is not relevant to this thread to begin with since, as far as I can tell, nobody here has referenced starting a track session or a race with tires that were about to cord. And, in the interest of safety, I hope nobody has plans to do so.
__________________
|
|
Appreciate
0
|
10-06-2009, 10:27 AM | #55 | |
Major General
374
Rep 8,033
Posts |
Quote:
__________________
|
|
Appreciate
0
|
10-06-2009, 10:46 AM | #56 | |
Major General
812
Rep 7,888
Posts |
Quote:
|
|
Appreciate
0
|
10-06-2009, 02:27 PM | #57 |
Major General
374
Rep 8,033
Posts |
More interesting stuff; didn't know that you could get grip out of corded tires.
__________________
|
Appreciate
0
|
10-06-2009, 02:32 PM | #58 | |
Major General
812
Rep 7,888
Posts |
Quote:
And they really do lose grip at this point |
|
Appreciate
0
|
10-06-2009, 02:38 PM | #59 | |
Major General
374
Rep 8,033
Posts |
Quote:
__________________
|
|
Appreciate
0
|
10-06-2009, 10:45 PM | #60 |
Lieutenant General
609
Rep 10,407
Posts |
Another test I would love to do (as much as it would likely not even be rigorous and would only be a single data point) is to run back to back two sets of PS2, one say <10k mi, <6 months old, around 50% worn, vs. a new then immediately shaved set of PS2's, shaved just into the wear bar or say slightly above the wear bar. I think their is ample evidence and opinion here that they would be very close in traction or perhaps the latter having some advantage. I think the only way this could be the case is if those of us who have experienced significantly observable traction loss under a similar extreme wear scenario are also feeling significant negative/confounding heat/UV/aging effects.
As with many complex things I examine I simply like to see consistency among anecdote, testing, theory, common sense, etc. and this one is vexing...
__________________
E92 M3 | Space Gray on Fox Red | M-DCT | CF Roof | RAC RG63 Wheels | Brembo 380mm BBK | | Vorsteiner Ti Exhaust | Matte Black Grilles/Side Gills/Rear Emblem/Mirrors | | Alekshop Back up Camera | GP Thunders | BMW Aluminum Pedals | Elite Angels | | XPEL Full Front Wrap | Hardwired V1 | Interior Xenon Light Kit | |
Appreciate
0
|
10-07-2009, 02:29 PM | #61 |
Private
11
Rep 91
Posts |
Hmmm, essentially comparing a "half aged" tire versus a new shaved tire? I would have to think that the new shaved would always outperform, either by a little, or by a lot, depending on how aged the old tire is. But that's based on the conventional wisdom.
As an anecdote, I put a LOT of heat cycles on the PS2s on my GT3 when I first got it. After 25-30 track days, they had <10k miles, ~50% tread still left (wasn't driving the car hard yet), although they were more like ~1-1.5 yrs old and not <6 months. Car was garaged when not going to the track, so UV degradation shouldn't really be a factor. But I can tell you with that many heat cycles at that point in their lifecycle, they were hard as rocks, you could easily feel the difference in hardness when touching them. Those would obviously be expected to perform much worse than a new shaved set of tires, but this is an extreme. So maybe to tighten up the description of the older tire, maybe you would need to define it as worn down to 50% by "street" use without significant track heat cycles? Conventional wisdom would say that the half aged tire should not outperform the new shaved tire. If not aged a lot, the older tire could perform close to the new shaved - but seems doubtful it would be better. Oh, and by "new" I assume you mean broken in new, not literally "just came out of the mold and has never touched the road" new. I'm not sure there is inconsistency, just a lot of variables in play.
__________________
Golden Gate BMWCCA - Car Control Clinics
'13 C4S/'12 328i/'04 GT3 Past: '09 M3 DCT/'03 M3 SMG/'95 M3... missing an E30 I suppose... |
Appreciate
0
|
Post Reply |
Bookmarks |
Thread Tools | Search this Thread |
|
|