17" Cup Wheels on 928S4?
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#17
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Quote:
Originally Posted by vsteinh
225 in front and 255 in the back would be possible? But what would be the exact size? 225/35 17 and 255/35 17?
If you don't mind understeer you will be fine.
I wouldn't do it.
I run 245 fronts and 275 rears on 18" CLWs - much improved handling.
Originally Posted by vsteinh
225 in front and 255 in the back would be possible? But what would be the exact size? 225/35 17 and 255/35 17?
If you don't mind understeer you will be fine.
I wouldn't do it.
I run 245 fronts and 275 rears on 18" CLWs - much improved handling.
I agree. Even with a 275 size tire, the car breaks loose easily, especially with mild upgrades to intake and exhaust.
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I just bought a set of these What tires do you run on them?
A 275 or 285 would probably be fine in the back. Lots of space there and I have no spacers.
I really like these rims. They are light, modern looking, BBS quality and an actual Porsche part rather than aftermarket.
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Hello,
I finally bought slightly different wheels - also because of the helpfull comments of you guys.
Now I got:
7,5 x 17 ET 65
9 x 17 ET 55
Can you tell me what the best/biggest size for the tires is?
Thanks again for your help. I'm getting close....
I finally bought slightly different wheels - also because of the helpfull comments of you guys.
Now I got:
7,5 x 17 ET 65
9 x 17 ET 55
Can you tell me what the best/biggest size for the tires is?
Thanks again for your help. I'm getting close....
#20
Instructor
Where did you find your wheels in the end? I'm trying to find a proper set as well.
Those are the correct sizes for the GTS OEM wheels. Tire sizes from the factory were
225-45/17 (Front)
255-40/17 (Rear)
...but whether those are "best" or not is more of a debate. Regardless of what you put on, you'll want something which is close to the total diameter of the whole package. Figuring that out isn't difficult but requires a few steps.
What you need is the rim diameter plus two-times the sidewall height.
The sidewall height can be calculated in inches as follows:
(Section Width) * (Sidewall %) / 25.4
So for the tire sizes above:
Front: 225 * 45% = 101.25 / 25.4 = 3.99"
Rear: 255 * 40% = 102 / 25.4 = 4.02"
Therefore total diameter for each:
Front: 17" + (2 * 3.99") = 25"
Rear: 17" + (2 * 4.02") = 25"
So, for example, a 235/40 on that front rim gives a total diameter of 24.4", which is 97.6% of the original diameter.
Probably close enough not to matter, assuming the width fits under the fenders, but I wouldn't want to see it much farther away from the original size.
Those are the correct sizes for the GTS OEM wheels. Tire sizes from the factory were
225-45/17 (Front)
255-40/17 (Rear)
...but whether those are "best" or not is more of a debate. Regardless of what you put on, you'll want something which is close to the total diameter of the whole package. Figuring that out isn't difficult but requires a few steps.
What you need is the rim diameter plus two-times the sidewall height.
The sidewall height can be calculated in inches as follows:
(Section Width) * (Sidewall %) / 25.4
So for the tire sizes above:
Front: 225 * 45% = 101.25 / 25.4 = 3.99"
Rear: 255 * 40% = 102 / 25.4 = 4.02"
Therefore total diameter for each:
Front: 17" + (2 * 3.99") = 25"
Rear: 17" + (2 * 4.02") = 25"
So, for example, a 235/40 on that front rim gives a total diameter of 24.4", which is 97.6% of the original diameter.
Probably close enough not to matter, assuming the width fits under the fenders, but I wouldn't want to see it much farther away from the original size.
Last edited by CardinalCar; 11-15-2013 at 07:41 PM. Reason: speeling
#21
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Following you advice, I would take
Front: on the 7.5x17: 235/40/17. -2.28%
Rear: on the 9x17: 265/40/17. +1.28%
Do you think they would fit on the wheel - and in the wheel house?
Thanks
Front: on the 7.5x17: 235/40/17. -2.28%
Rear: on the 9x17: 265/40/17. +1.28%
Do you think they would fit on the wheel - and in the wheel house?
Thanks
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Following you advice, I would take
Front: on the 7.5x17: 235/40/17. -2.28%
Rear: on the 9x17: 265/40/17. +1.28%
Do you think they would fit on the wheel - and in the wheel house?
Thanks
Front: on the 7.5x17: 235/40/17. -2.28%
Rear: on the 9x17: 265/40/17. +1.28%
Do you think they would fit on the wheel - and in the wheel house?
Thanks
#24
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Hello I checked several sources and I believe a 275 tire on a 9" rim is not possible. Even if I loved to...
Besides this, the combination 235/40/17 and 265/40/17 seems not to be possible to
order.
Nevertheless the combination 235/45/17 and 265/40/17 is possible. Both tires are slightly higher than the original sized tires. 25.33 and 25.35 inch. I hope this is not a big issue.
Besides this I found the Bridgestone Potensa RE760 Sport tires. Do you have any experiense this these tires?
Thanks
Volkmar
Besides this, the combination 235/40/17 and 265/40/17 seems not to be possible to
order.
Nevertheless the combination 235/45/17 and 265/40/17 is possible. Both tires are slightly higher than the original sized tires. 25.33 and 25.35 inch. I hope this is not a big issue.
Besides this I found the Bridgestone Potensa RE760 Sport tires. Do you have any experiense this these tires?
Thanks
Volkmar
#25
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Hello I checked several sources and I believe a 275 tire on a 9" rim is not possible. Even if I loved to...
Besides this, the combination 235/40/17 and 265/40/17 seems not to be possible to
order.
Nevertheless the combination 235/45/17 and 265/40/17 is possible. Both tires are slightly higher than the original sized tires. 25.33 and 25.35 inch. I hope this is not a big issue.
Besides this, the combination 235/40/17 and 265/40/17 seems not to be possible to
order.
Nevertheless the combination 235/45/17 and 265/40/17 is possible. Both tires are slightly higher than the original sized tires. 25.33 and 25.35 inch. I hope this is not a big issue.
Personally, I am not convinced that fitting wider tires on the same width rims always buys you anything (except maybe looks). More rubber, yes, but a wider tire on the same rim also rolls more, and won't handle as crisply. It all depends on what's important to you.
Using the Tirerack spec's for the Bridgestone RE760's that you mentioned, a 7.5" rim is the minimum width recommended for a 235/45. If you went with the 225/45 then 7.5" is the reference width, with a range of 7-8.5". Being in the middle of the fitment range is good, I think.
Same with the rears, the 265/40 puts the 9" rim at the minimum of the range, while it is the reference width for the 255/40.
The larger diameter is not a big deal, your speedo will read a bit mph low and you will have effectively stretched the gear ratio a few percent. S4's are already geared pretty tall, but it is a relatively small effect.
Personally we have stuck with the 225/45-17 and 255/40-17 sizes that Porsche used for those wheels (we have two sets, for the S4 and the GTS). Our GT is on 235 & 265, but on wider 18" rims.
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Same with the rears, the 265/40 puts the 9" rim at the minimum of the range, while it is the reference width for the 255/40.
http://www.ebay.com/itm/Porsche-Pana...54aab7&vxp=mtr
#27
Rims for my 1984 Porsche 928S
Hi Guys
I read so much about which rims I can put on my 928S.
I would like to put 17" or 18" tops - which rims are the best fit and wont effect the ride and handling?
PLEASE HELP ME
Thanks
I read so much about which rims I can put on my 928S.
I would like to put 17" or 18" tops - which rims are the best fit and wont effect the ride and handling?
PLEASE HELP ME
Thanks
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#29
hey could you elaborate on the et47 being bad im looking at some with 7.5x17 et52 and 9x17 et47 rear