Tires and Alignment

SockGuy

SockGuy

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I am about to change out the OEM Michelin Super Sport with Michelin Pilot AS4’s on my 2018 Grand Sport. Is anyone else running the AS4’s and if so, are you liking them?
Is there a noticeable difference in ride or noise level?
Will also be doing an alignment. Has anyone changed the GM alignment spec on their Grand Sport.
I had 26,000 on the original tires, all 4 are at their cords on the inside edge.
 
SockGuy said:
I am about to change out the OEM Michelin Super Sport with Michelin Pilot AS4’s on my 2018 Grand Sport. Is anyone else running the AS4’s and if so, are you liking them?
Is there a noticeable difference in ride or noise level?
Will also be doing an alignment. Has anyone changed the GM alignment spec on their Grand Sport.
I had 26,000 on the original tires, all 4 are at their cords on the inside edge.
Click to expand...


Don't have them yet but the AS4 is what I will put on likely next fall. Members who have installed them seem to like them. If you go non run flats, the ride and noise level are both better. Not so sure for the run flat AS4.
As far as alignment goes, I first came aware of the excess camber with my C6 and inside edge wore to the cords. When I bought my C7 I had my dealer back of the camber/caster away from the performance track settings. 27,000 later and no inside edge wear at all. There has been lots of posts and warnings here over the years on this subject and early tire wear. I don't track my car but saw no difference in cornering and handling with the less aggressive alignment.
This is really close to what I had them set mine at.

1666233320860.png
 
Thanks for the measurements, glad to hear no wear at these settings. Re you comment on ride and noise on run flats, From what I see, the specified size for fronts and rears on the GS are ZP or zero pressure, no choice.
 
SockGuy said:
Thanks for the measurements, glad to hear no wear at these settings. Re you comment on ride and noise on run flats, From what I see, the specified size for fronts and rears on the GS are ZP or zero pressure, no choice.
Click to expand...
Interesting. I would have thought you would have had a choice.
 
Finally changed out my original Michelin run flats (rear) at just over 56K. Was down to the wear bar but the main reason was that I had picked up a nail and had a high rate pressure leak. Managed to get home because i carry a compressor with me. At any rate, it really surprised me that the Pilot SS run flats lasted this long. Don't track and very rarely spin the rear tires.
 
I can't comment on the AS4's as I've not used them, but I will offer some feedback regarding the alignment process. Have a look at this post.

Make sure that your servicing agent is using alignment specs for the C7 FE6/FE7 suspension options as a basis to start with. These are specific to the GS/Z06 and the GS/Z06 with the Z07 package. FE3 and FE4 specs are for the base Stingray and Stingray with Z51 option and should not be applied to wide body C7's. You'd be surprised how many dealers don't know the difference. Also, make absolutely sure that your servicing agent has the rear caster adapter and angle gauge needed for checking/setting the rear caster and that they know how to use it. This is the starting point for a proper alignment on a C7 and, unless the rear caster is set within factory spec, the rest of the alignment will be off.

The primary reason that the inside edges of all 4 tires are worn is because the factory alignment is too aggressive, typical for GS and Z06 C7's. It's usually a result of excessive negative camber and toe settings, both front and rear. Theoretically, the closer you can get to "zero", for camber and toe, the more "street friendly" your alignment will be. Although it's not possible to achieve "zero" settings on FE6/FE7 suspensions, you can get close. See the included alignment spec sheet for the settings applied to my GS which has 18,000 kl's on it with perfectly even, measured wear on all 4 tires. Also note that the rear caster spec is penned in at the bottom. That's because most, if not all, dealer/specialist alignment equipment does not measure rear caster, it must be done manually using the adaptor and angle gauge.

I can't stress enough the importance of the rear caster setting. Finding a qualified alignment specialist that has the adaptor and angle gauge is imperative to achieving a proper "street friendly" alignment, or any alignment, on a wide body C7. That, combined with the less aggressive camber and toe settings, will give you the increased tire life you're looking for. Without these things you'll probably be back in the same boat in 20-25 thousand kilometers or less.

Hope this helps.
Ross


c7.algnmt.04.ja.pg.1.jpg
 
SockGuy said:
You had much better luck than I did with the SS’s
Click to expand...
Actually kept one tire as a spare as it still had some life left in it, maybe one MM of thread before the wear bar. Never know if it would come in handy if I blew a tire and needed a quick replacement for whatever reason.
 
II dont track or race my cars so I want to get less camber in the front and back. On my C6 ZR1 , there is plenty of adjustment, I now have -.3 negative camber on 4 wheels and oem spec. for the toe and camber. the ride is way less agressive + tires wear evenly and last longer. On my Gransport the rear is the issue as the oem toe link dosen't provide enought toe adjustment when you set the rear camber to-.75 or less. I replace the oem link with these '' Granatelli Rear Adjustable Toe Links | C7 '' . The front of the C7 can reach about -.4 negative camber keeping the oem spec for toe and caster without any modifications I matched the rear and I now have -.4 negative on 4 wheels. As the C6, the car have a way more enjoyable ride, it doesn't try to ripe the steering wheels of your hands as much as with the oem camber and better tire life. The toe link take about 1 hrs to install, with major alignement correction like this, I always do a first run of correction then I take the mesurement a second time to make the fine tune. Take more time but the results are great. I did 3 this summer and a last one for the season next week. So far, all happy clients. I was ask about handling lost because of camber change. After 3000km this summer I can tell you that the car is still a beast when you push it in tight curves, the tires are so large, they still stick like crazy to the road and my driving skills wont go over what these 2 cars have to offer
 
C SEVEN GS Bob said:
Here is an alignment spec that some have used with success.
View attachment 101877
Click to expand...
This is the same settings-sheet that is in my C7 files - for if I find excessive inner tread wear when replacing my original tires.
It's coming up soon as I just sourced AS4ZP's for my Z51C7 after another C-Gen owner I know just installed a set and likes them quite a bit. I have been waiting for size availability and finally found them after being hinted that prices may increase quite a bit in the New Year. Almost getting the GST back too with a Fall'22 rebate from Michelin.
 
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SN3 said:
This is the same settings-sheet that is in my C7 files - for if I find excessive inner tread wear when replacing my original tires.
It's coming up soon as I just sourced AS4ZP's for my Z51C7 after another C-Gen owner I know just installed a set and likes them quite a bit. I have been waiting for size availability and finally found them after being hinted that prices may increase quite a bit in the New Year. Almost getting the GST back too with a Fall'22 rebate from Michelin.
Click to expand...
I get mine put on on Tuesday, with alignment. Found that some dealers could not source them whereas other had no problem to do so.
 
... it can be a local sourcing thing at certain times of the year ...
Found that Michelin Distributing/Warehousing is not expecting any more of C7Z51 size/spec until after Feb 2023 when increased pricing will be in place - so my normal big-box go-to for supply only was out. Had to find a local tire dealer who already had my exact AS4ZP size/spec in their own network/inventory. Only found one source and my set will be coming from BC & Ont to me in AB.
 
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SN3 said:
... it can be a local sourcing thing at certain times of the year ...
Found that Michelin Distributing/Warehousing is not expecting any more of C7Z51 size/spec until after Feb 2023 when increased pricing will be in place - so my normal big-box go-to for supply only was out. Had to find a local tire dealer who already had my exact AS4ZP size/spec in their own network/inventory. Only found one source and my set will be coming from BC & Ont to me in AB.
Click to expand...
I had debated on waiting till spring but decided to do it now to avoid possible lack of stock in the spring and probable price increases. Install on Tuesday, car will go to storage before the weekend. I will be ready for spring when it arrives in Ontario.
 
Got 40k kms out of the MPSS OEM run flats (2019 Z51 7spd). It was corded on the front insides and blew the front passenger side out on a back road. Had it to the track a couple of times and drive pretty aggressively. I lowered the car all the way on the stock bolts (maybe an inch or so)

I dont care about squeezing as many kms as I can out of a set of tires. I want the car to handle well and be sharp on turn in and in the corners. Quite happy that i got 40k kms out of the set particularly after seeing the specs

I replaced the tires with the AS4 ZP's. I went with the FE6/7 alignment specs for the GS and Z as they are a little more aggressive on the camber. Heres the pre and post sheet. Camber will increase wear but its usually toe that is the killer. They used the rear caster tool and angle gauge.

Liking the AS4's so far.


20220927_091907.jpg
 
Vern1 said:
Got 40k kms out of the MPSS OEM run flats (2019 Z51 7spd). It was corded on the front insides and blew the front passenger side out on a back road. Had it to the track a couple of times and drive pretty aggressively. I lowered the car all the way on the stock bolts (maybe an inch or so)

I dont care about squeezing as many kms as I can out of a set of tires. I want the car to handle well and be sharp on turn in and in the corners. Quite happy that i got 40k kms out of the set particularly after seeing the specs

I replaced the tires with the AS4 ZP's. I went with the FE6/7 alignment specs for the GS and Z as they are a little more aggressive on the camber. Heres the pre and post sheet. Camber will increase wear but its usually toe that is the killer. They used the rear caster tool and angle gauge.

Liking the AS4's so far.


View attachment 101931
Click to expand...
thanks for the numbers
 
Michelin Pilot AS4’s installed and I would say on my 100km drive home, they were definitely quieter and I would say smoother. Unfortunately, dealer was not able to perform the alignment I was hoping for, and he thought he could do :( he had new equipment but not the extra attachments required to set up a camber closer to zero. Interesting to mention that the alignment on the original tires was within GM spec when it was on the alignment rack, but tire wear was severe on all four tires on the inside edge at 26,000 kms. I am not an aggressive driver, never on a track…Be Aware!
I will leave the alignment until spring as car goes to storage this week. If anyone knows of an alignment shop in south western Ontario, that has the proper equipment to do this, I would appreciate if you could let me know.
 

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