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Help with tires

Have a set of HRE's coming (sizes below) and need help choosing correct tire sizes. I want Michelin PSS's.

Are any of you running similar setups? Photos would be awesome.


17x8.5 et48
17x10 et56


Tire sizes were as follows (but they looked too fat in the photos, so I bought wheels alone)

225/45/17
255/40/17


any help greatly appreciated!
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Old 07-25-2017, 01:52 PM
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Michelin Super sports have been replaced. There may still be old stock in your sizes but at this years parade Michelin put on a dog and pony show to introduce the new line. Cheers
Old 07-29-2017, 06:02 AM
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Quote:
Originally Posted by 99cobra66 View Post
Have a set of HRE's coming (sizes below) and need help choosing correct tire sizes. I want Michelin PSS's.

Are any of you running similar setups? Photos would be awesome.


17x8.5 et48
17x10 et56


Tire sizes were as follows (but they looked too fat in the photos, so I bought wheels alone)

225/45/17
255/40/17


any help greatly appreciated!
1st issue assuming this is for a n/b 964 is that the ET for the rears is not quite right. 10 will want an ET closer to 44 which can be accomplished w/ a 12mm spacer.

The front ET is pretty close to what most use, ie ET50 and should work well.

the tire choices are ideal for performance in that those are the widest wheels spec'ed for those tires.
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Old 07-29-2017, 06:24 AM
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Quote:
Originally Posted by Bill Verburg View Post
1st issue assuming this is for a n/b 964 is that the ET for the rears is not quite right. 10 will want an ET closer to 44 which can be accomplished w/ a 12mm spacer.

The front ET is pretty close to what most use, ie ET50 and should work well.

the tire choices are ideal for performance in that those are the widest wheels spec'ed for those tires.
ok thank you for the advice. Yes came off a nb 964 and going on one as well.

would you recommend a hub centric spacer or not? also will I need longer hub bolts as well?
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Old 07-30-2017, 12:16 PM
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I am running 964 3.6 turbo sizes on my C2 rears are 10ET 61 x 18 I can run them without spacers but I use a 5mm to make sure they don't rub on the inside. This brings you to ET56. I would run as you are. I am also running 265 rear but again in 18" sizes.
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Gone worth mentioning '71 E '79 SC, '79 built to '74 3.0 RS tribute (2390 # 270 hp), '80 928 euro 5 speed, '74 2.0l 914, '89 944 S2,'04 Cayenne TT '14 boxster, '14 Cayenne GTS many others
Old 08-01-2017, 04:35 PM
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Quote:
Originally Posted by Bill Verburg View Post
1st issue assuming this is for a n/b 964 is that the ET for the rears is not quite right. 10 will want an ET closer to 44 which can be accomplished w/ a 12mm spacer.

The front ET is pretty close to what most use, ie ET50 and should work well.

the tire choices are ideal for performance in that those are the widest wheels spec'ed for those tires.
The general rule of thumb for street us is at least 50%of the stud width, which means ~6mm spacer max w/o changing the studs.

Porsche used a 17mm double bolt spacer on these cars when needed
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Old 08-02-2017, 04:29 AM
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Quote:
Originally Posted by Cobalt View Post
I am running 964 3.6 turbo sizes on my C2 rears are 10ET 61 x 18 I can run them without spacers but I use a 5mm to make sure they don't rub on the inside. This brings you to ET56. I would run as you are. I am also running 265 rear but again in 18" sizes.
Interesting, definitely at the far end of the fitment bell curve
the next most 10" fitment I've seen is 10ET51 but w/ 275/35 x18 tires

you should probably try test fitting them w/o a spacer, the first contact point will be the oil line in the right rear wheel well.

These are 8ET50 w/ 245/35 x18 & 10ET65 w/either a 17 or 20mm spacer( I forget which) 275/35 x18 tires
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Old 08-02-2017, 04:36 AM
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Quote:
Originally Posted by Bill Verburg View Post
Interesting, definitely at the far end of the fitment bell curve
the next most 10" fitment I've seen is 10ET51 but w/ 275/35 x18 tires

you should probably try test fitting them w/o a spacer, the first contact point will be the oil line in the right rear wheel well.

These are 8ET50 w/ 245/35 x18 & 10ET65 w/either a 17 or 20mm spacer( I forget which) 275/35 x18 tires
My fronts are 8ET52 with a 225. Fit is perfect no spacers needed. No rubbing anyplace. I ran the rears without spacers. They did not rub the oil line but were very close. IMO these work perfectly. I tracked this car with these wheels for a number of years without any rubbing issues.

I did a comparison with Spyerx and if IIRC he claimed he could fit a 10ET 47 with a 275 in the rear. I mounted 15mm spacers on mine and tried to see how it would work. My Fikse's did not have the relief in the back for the spacer studs so I had to use my wheels from my turbo (same offset) but with a 285 rear and they sat way too far out. I rubbed going out my driveway. You can see the rub marks. It might be possible with a 275 or 265.






Isn't the rolling dia of a 275/35/18 25.6 " or a bit oversized? I run the N spec tire for my C2 which has a rolling dia of 25" Also these do not rub the trailing arm which is also a concern.


BTW as always Dan does nice work. Love the color.
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Gone worth mentioning '71 E '79 SC, '79 built to '74 3.0 RS tribute (2390 # 270 hp), '80 928 euro 5 speed, '74 2.0l 914, '89 944 S2,'04 Cayenne TT '14 boxster, '14 Cayenne GTS many others
Old 08-02-2017, 05:18 AM
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Quote:
Originally Posted by Cobalt View Post
My fronts are 8ET52 with a 225. Fit is perfect no spacers needed. No rubbing anyplace. I ran the rears without spacers. They did not rub the oil line but were very close. IMO these work perfectly. I tracked this car with these wheels for a number of years without any rubbing issues.

I did a comparison with Spyerx and if IIRC he claimed he could fit a 10ET 47 with a 275 in the rear. I mounted 15mm spacers on mine and tried to see how it would work. My Fikse's did not have the relief in the back for the spacer studs so I had to use my wheels from my turbo (same offset) but with a 285 rear and they sat way too far out. I rubbed going out my driveway. You can see the rub marks. It might be possible with a 275 or 265.





Isn't the rolling dia of a 275/35/18 25.6 " or a bit oversized? I run the N spec tire for my C2 which has a rolling dia of 25" Also these do not rub the trailing arm which is also a concern.


BTW as always Dan does nice work. Love the color.
Spyrex tried 10ET ET43 275/35 x18, he reported it to be not a good fit
he now has 10ET51 275/35 x18 and likes it

here is some further data
chakka 964RSA
8.5x18 45 235/40MPSC
10x18 50 265/35MPSC 15mm spacer massaged lips, flat oil line 600/800# springs

Spyerx 964 BBS E88
8.5x18 48 0288107ctr 1.5/7 235/40 NT01
10x18 43 doesn't work at this height 275/35 NT01
10x18 51 0288108ctr 2/8 halfs 275/35 NT01

ThomasC2/BBSE28
8x18 50 225/40x18 MPSC
10x18 65 21mm spacer =ET44 265/35x18 MPSC

Magnus E. Kinessis K5 Factory overall front back front back calc
8.5 x18 40 9.5 3.25 6.25 241.3 158.75 38 245/35 x18 R7
10 x18 45 11 3.75 7.25 279.4 184.15 44 275/35 x18 R7
225/40x18

275/35 x18 generally run 25.5 to 25.6" unmounted OD, installed depends on wheel width and car weight and air pressure.

265/35 x18 run 25.2 to 25.3" OD unmounted

for street uses ome might be concerned by the affect on the odometer, for track use the trade off is width(grip) vs height(gearing)
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Old 08-02-2017, 08:29 AM
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Here's a chart w/ a bunch of 9.5 & 10' rear fitments and ET for n/b 964, most use 265 or 275 tires
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Old 08-02-2017, 11:33 AM
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Quote:
Originally Posted by Bill Verburg View Post
Spyrex tried 10ET ET43 275/35 x18, he reported it to be not a good fit
he now has 10ET51 275/35 x18 and likes it

here is some further data
chakka 964RSA
8.5x18 45 235/40MPSC
10x18 50 265/35MPSC 15mm spacer massaged lips, flat oil line 600/800# springs

Spyerx 964 BBS E88
8.5x18 48 0288107ctr 1.5/7 235/40 NT01
10x18 43 doesn't work at this height 275/35 NT01
10x18 51 0288108ctr 2/8 halfs 275/35 NT01

ThomasC2/BBSE28
8x18 50 225/40x18 MPSC
10x18 65 21mm spacer =ET44 265/35x18 MPSC

Magnus E. Kinessis K5 Factory overall front back front back calc
8.5 x18 40 9.5 3.25 6.25 241.3 158.75 38 245/35 x18 R7
10 x18 45 11 3.75 7.25 279.4 184.15 44 275/35 x18 R7
225/40x18

275/35 x18 generally run 25.5 to 25.6" unmounted OD, installed depends on wheel width and car weight and air pressure.

265/35 x18 run 25.2 to 25.3" OD unmounted

for street uses ome might be concerned by the affect on the odometer, for track use the trade off is width(grip) vs height(gearing)

We know Magnus did a bit more than message his fenders and most of the others are the extremes. for Street use I personally think the ET 50-56 are more then enough and that would be dependent on suspension.

I must assume some of these cars vary from stock and most likely had some rolling and messaging going on. But it is good info to have especially for track use.

For the OP although 18's the offsets are what you want to see and I found this picture which might give you a good idea. Your fronts would be pushed out by 10mm vs mine.
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Gone worth mentioning '71 E '79 SC, '79 built to '74 3.0 RS tribute (2390 # 270 hp), '80 928 euro 5 speed, '74 2.0l 914, '89 944 S2,'04 Cayenne TT '14 boxster, '14 Cayenne GTS many others
Old 08-02-2017, 12:35 PM
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Here's a comparison of the full specs for Cobalt's 964 on left an you proposed on the right
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Old 08-02-2017, 02:03 PM
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Quote:
Originally Posted by Bill Verburg View Post
Here's a comparison of the full specs for Cobalt's 964 on left an you proposed on the right
Bill,

Am I reading this correctly? If you go from a 62.3mm front space to a 72.65 front space then shouldn't his wheels be pushed out 10.35mm outer lip and out 2.35mm inside? Or are you saying by showing them - you will have less clearance with these numbers?

Also his rears are 10" wide vs 9.5. Both ET's are 56 so there should be no material change other than tire size.
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Gone worth mentioning '71 E '79 SC, '79 built to '74 3.0 RS tribute (2390 # 270 hp), '80 928 euro 5 speed, '74 2.0l 914, '89 944 S2,'04 Cayenne TT '14 boxster, '14 Cayenne GTS many others
Old 08-03-2017, 04:52 AM
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Quote:
Originally Posted by Cobalt View Post
Bill,

Am I reading this correctly? If you go from a 62.3mm front space to a 72.65 front space then shouldn't his wheels be pushed out 10.35mm outer lip and out 2.35mm inside? Or are you saying by showing them - you will have less clearance with these numbers?

Also his rears are 10" wide vs 9.5. Both ET's are 56 so there should be no material change other than tire size.
I ran several options for comparison guess I posted the wrong one
This should be the relevant comparison


yes, for tire and wheel f/s or b/s delta positive is further from the wheel centerline

for the clearance section positive is closer to the relevant impediment(lip or innerwall)

vertical positive is a taller tire
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Old 08-03-2017, 07:34 AM
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thank you all for your help!

I went with the above tire sizes (Michelin PS2's) and ordered some 7 and 12mm spacers to try on the rears. I will use one or the other, or maybe none. Will post pics
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Old 08-03-2017, 01:51 PM
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Quote:
Originally Posted by Bill Verburg View Post
yes, for tire and wheel f/s or b/s delta positive is further from the wheel centerline

for the clearance section positive is closer to the relevant impediment(lip or innerwall)

vertical positive is a taller tire

That is what I thought. So shouldn't the numbers you have posted be positive vs negative for the 8.5 ET 48 over the 8 ET 52? Everything I come up with shows the 8.5 being pushed out closer to the lip by 10mm and to the inside by 2mm?
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Gone worth mentioning '71 E '79 SC, '79 built to '74 3.0 RS tribute (2390 # 270 hp), '80 928 euro 5 speed, '74 2.0l 914, '89 944 S2,'04 Cayenne TT '14 boxster, '14 Cayenne GTS many others
Old 08-04-2017, 04:29 AM
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Quote:
Originally Posted by Cobalt View Post
That is what I thought. So shouldn't the numbers you have posted be positive vs negative for the 8.5 ET 48 over the 8 ET 52? Everything I come up with shows the 8.5 being pushed out closer to the lip by 10mm and to the inside by 2mm?
It is, look in the data, right side. Wheel & tire f/s & bs delta is listed
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Old 08-04-2017, 05:50 AM
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