991.2 GTS Tire/Wheel Sizes
Rennlist Member
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From: On a road to nowhere.
I'm guessing you had a typo and meant 325/25/21, yes? Because the stock CL size is 305/30/20. If you went wider and larger profile, you'd wind up way, way larger diameter than stock.
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You can probably run a Toyo R888 but that is one crappy tire.
Pro
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Sorry. I meant to say a 25 series sidewall.
Michelin Pilot Sport 4S
325/25ZR21
102Y XL BSW 27.4"13.2"11.5-12.5"12"9.5/32"XL1874 lbs50 psi28.7 lbs760
^The bolded part "27.4" is the rolling diameter of the tire.
Here is the stock Pirelli P Zero tire size/rolling diameter:
305/30ZR20
99Y SL BSW 27.3"12.5"10.5-11.5"11"9/32"SL1709 lbs51 psi29 lbs762
27.3 inches..
So excuse me. I'm very tired.. The difference is 0.1".. Still nothing to set off any alarms or sensors.. The car won't know. The rolling diameter changes ever so slightly as the tire wears out anyway.
I'm running Pilot Sport CUP 2 in the same stock size as the pirelli and it's rolling diameter is 27.2".. My speedo and all systems function flawlessly.
There is a 345/30/20 CUP 2 but if feel as if that's too wide for the rear 12" wheel and the rolling diameter for that is 27.7".. I'm sure that would work but it's too tall for my taste.
Michelin Pilot Sport 4S
325/25ZR21
102Y XL BSW 27.4"13.2"11.5-12.5"12"9.5/32"XL1874 lbs50 psi28.7 lbs760
^The bolded part "27.4" is the rolling diameter of the tire.
Here is the stock Pirelli P Zero tire size/rolling diameter:
305/30ZR20
99Y SL BSW 27.3"12.5"10.5-11.5"11"9/32"SL1709 lbs51 psi29 lbs762
27.3 inches..
So excuse me. I'm very tired.. The difference is 0.1".. Still nothing to set off any alarms or sensors.. The car won't know. The rolling diameter changes ever so slightly as the tire wears out anyway.
I'm running Pilot Sport CUP 2 in the same stock size as the pirelli and it's rolling diameter is 27.2".. My speedo and all systems function flawlessly.
There is a 345/30/20 CUP 2 but if feel as if that's too wide for the rear 12" wheel and the rolling diameter for that is 27.7".. I'm sure that would work but it's too tall for my taste.
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Thread Starter
Three Wheelin'
Joined: Feb 2018
Posts: 1,784
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From: Greenwich, CT
Ok, so now I know I am sticking with stock size..
What will it be Michelin Cup 2 or the 4S?
Keep in mind I am using these exclusively as a summer tire and not tracking the car, so leaning towards 4S.
Are these made in the N1 or just N0?
Thanks for the help guys..
What will it be Michelin Cup 2 or the 4S?
Keep in mind I am using these exclusively as a summer tire and not tracking the car, so leaning towards 4S.
Are these made in the N1 or just N0?
Thanks for the help guys..
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Joined: Oct 2011
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From: San Diego
And please do not confuse the R888 with the R888R. Completely different tires and has been discussed multiple times on Rennlist.
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Cup 2 N1.. do it and I bet you're going to post about how happy you are. Cup 2 are not dangerous in wet conditions like a Toyo R888 but they're not great. 4S better wet grip but not as responsive as Cup 2.
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Three Wheelin'
Joined: Feb 2018
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From: Greenwich, CT
Yeah, but those Cup 2's have really little tread and wear out fast. Primarily for track use and probably the best track tire but, I think 4S is the way to go for strictly street use.
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Wouldnt shock me if the more narrow Cup 2 N1 designed for Porsche out did the r888r you mentioned above.
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I got about 10k miles out of the P zeros before the rears were bald on the inside.
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From: On a road to nowhere.
Getting aftermarket wheels right is a little complicated.
I opted for the 5-lug 11.5" Carrera S wheels instead of the CL 12" Turbo S wheels. I picked up the car in early February, so had the dealer mount my winter Michelin's on the stock wheels and they will be my winter setup.
The stock wheel specs are:
I'm going to be ordering new aftermarket wheels to use for my summer setup. I have the stock MPS4S tires in my basement, which are 245/35/20 and 305/30/20 (same as the winter tires). But I'm thinking to put 9" and 12" wheels on (which are .5" wider front and back), and which are similarly sized to the default CL wheels for the GTS.
Determining the proper offset, though, is more complicated than just figuring out what is flush and what will clear the suspension. I want to be a bit more flush, particularly in the front, safely away from the brakes and suspension, but I also don't want to change the scrub-radius much, if at all, as even small changes can affect handling dynamics.
I like this wheel and tire fitment calculator. https://www.wheel-size.com/calc/. It shows that I could probably go with 12" wide rears with a offset of 52 to get about 10mm closer to flush, about 2mm closer to the suspension, and only very minimally change from a zero scrub radius to about 4mm of positive scrub radius, which is hopefully not too significant in terms of handling. I like that the calculator even estimates the different impact of the change on the tires and wheel (the wheel is a half inch wider, but the tire width will stretch a bit, about 4mm) as well.
I'll need to verify all this with the various wheel vendors, and I need to work on the front offset as well. But this is the sort of crap I agonize over when figuring out aftermarket wheels with different specs than stock.
I opted for the 5-lug 11.5" Carrera S wheels instead of the CL 12" Turbo S wheels. I picked up the car in early February, so had the dealer mount my winter Michelin's on the stock wheels and they will be my winter setup.
The stock wheel specs are:
8.5x20 et49
11.5x20 et56
I'm going to be ordering new aftermarket wheels to use for my summer setup. I have the stock MPS4S tires in my basement, which are 245/35/20 and 305/30/20 (same as the winter tires). But I'm thinking to put 9" and 12" wheels on (which are .5" wider front and back), and which are similarly sized to the default CL wheels for the GTS.
Determining the proper offset, though, is more complicated than just figuring out what is flush and what will clear the suspension. I want to be a bit more flush, particularly in the front, safely away from the brakes and suspension, but I also don't want to change the scrub-radius much, if at all, as even small changes can affect handling dynamics.
I like this wheel and tire fitment calculator. https://www.wheel-size.com/calc/. It shows that I could probably go with 12" wide rears with a offset of 52 to get about 10mm closer to flush, about 2mm closer to the suspension, and only very minimally change from a zero scrub radius to about 4mm of positive scrub radius, which is hopefully not too significant in terms of handling. I like that the calculator even estimates the different impact of the change on the tires and wheel (the wheel is a half inch wider, but the tire width will stretch a bit, about 4mm) as well.
I'll need to verify all this with the various wheel vendors, and I need to work on the front offset as well. But this is the sort of crap I agonize over when figuring out aftermarket wheels with different specs than stock.
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From: San Diego
Whats your experience with the R888R's? You found them rough and noisy? You didn't think they performed better that the Cup 2's?
Thread Starter
Three Wheelin'
Joined: Feb 2018
Posts: 1,784
Likes: 642
From: Greenwich, CT
V999: You made a point I forgot to mention.. On the GTS cars with PCCB there have been a few stories of guys who had their calipers mangled up when a pebble got lodged between the wheel and the caliper. By moving the wheel further away from the caliper (significantly) there is no chance for that to happen. Stock wheels are tight to the caliper, AM wheels allow for more clearance.
As far as winter wheels, they are always more narrow than summer, even Porsche spec's them that way. On Summer you want more rubber to the road patch and in snow you want less, so they are thinner.
As far as winter wheels, they are always more narrow than summer, even Porsche spec's them that way. On Summer you want more rubber to the road patch and in snow you want less, so they are thinner.