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Discussion summary
YOUR RESEARCH19'' wheels on 996 C4
Reported or suspected cause
all-wheel drive system and the need
Suggestion or failed attempt
No successful repair reported for this finding.
0
Identified cause
1
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0
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Read evidence and context
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Discussions that suspect a cause
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Suspected cause
The is due to the all-wheel drive system and the need for some sort of factory spec'd front to rear diameter difference parameter (which I am not able to locate and wish I could).
Leading evidence: 'all-wheel drive system and the need' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'all-wheel drive system and the need' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Run 40 front, 30 rear aspects' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
That is why C4 type drives run the 40 front, 30 rear aspects.
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Suggestion
There are people running 997 sizes on the 996 AWD, and supposedly it works OK from the AWD standpoint.
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Suggestion
I don�t have a C4, but I�m running 997S wheels with 235/35 19 and 295/30 19.
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Suggestion
So would 315/25/19 which we used on the 996 Turbo below.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
all-wheel drive system and the need
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
Read evidence and context
Discussions that suspect a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suspected cause
The is due to the all-wheel drive system and the need for some sort of factory spec'd front to rear diameter difference parameter (which I am not able to locate and wish I could).
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
13 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261027T042512Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I don�t have a C4, but I�m running 997S wheels with 235/35 19 and 295/30 19. A lot will depend on the wheels due to offset. Mine are 19x11 et 67 rear with 19x8 et 57 with a 14 mm spacer.
Picture from a week long road trip to Maine last year.
I am not sure, but the tire sizes you referred to may not work on a C4. The is due to the all-wheel drive system and the need for some sort of factory spec'd front to rear diameter difference parameter (which I am not able to locate and wish I could). I have been told that not adhering to that parameter could cause the all-wheel drive components to malfunction and/or break. That is why C4 type drives run the 40 front, 30 rear aspects.
While that may be correct concerning tire sizes for a 997, I believe the OP is talking about a 996, in which case those sizes would be incorrect.............I think.
Since 19s never came on a 996, and they did on the 997, I would think that it makes the most sense to replicate what Porsche put on the AWD 997 cars that came with 19s. The OPs tires choices in the first post both appear to be off by comparison.
I know it�s a turbo vs C4, but these are 235/35 19 and 305/30 19 on LMs. 11 inch wide rear.
Yes, I had 19" wheel on my 2002 996.
The ride was harsh.
The wheels had more unsprung weight and so turning was a little more labored.
The fronts would scrub in the fender well liner in sharp turns.
Even though the tires were lower profile (height) to compensate, the car was a little higher off the ground compared to 18". This had to do with the overall outer diameter of the wheel.
If you look closely, the line of the fender doesn't seem perfectly matched with 19" wheels on the 996. Those that attempt 20" wheels look even worse. Looks like a wagon wheel.
I went back to OEM Turbo Twists and it was amazing lighter the steering felt... as well as the car felt more in control.
The 997 has a different front diff ratio to make the 997 size tires work correctly. Optimum size for 996 cars would be 235/35-19 and 315/25-19. The 315/25 size is virtually unobtainable. There are people running 997 sizes on the 996 AWD, and supposedly it works OK from the AWD standpoint. Fitment may be another issue. Factory 997 sizes are 235/40-19 and 305/30-19 or 225/40-19 and 295/30-19.
Agreed. I saw that the 997s came with 295 rears, but wasn�t sure if they were on the standard C4 or just the 2wd cars.
And agreed on fitment. Wheel size is very important, width/et. The BBS are snug with 305s due to an aggressive offset. I�m also about to try and fit a 305 vs the current 295. Not a lot of room to play with due to the 19x11 et 67 wheels.
To answer your question, no, 19" wheels will not cause any issues on a 996 C4 as long as the wheel's widths & offsets are correct. You also have to be within +/- 2% of the factory tire's rolling diameter.
225/35/19 would have a correct tire height. A 275/30/19 would be 3% larger than the factory rear tire so that is not recommended. A 295/25/19 would be a correct height. So would 315/25/19 which we used on the 996 Turbo below. 996 Turbo and 996 C4 can use the same aftermarket wheel fitments.
This is a source reference. Confirm exact model applicability in the original material.
