12 captured repliesPartial discussion capture · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH235's or 245's
Leading reported evidence
Install michelin ps 4's
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
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.
Performed · outcome unconfirmed · Original poster
I have recently fitted Michelin PS 4's to the rear 305/30/19 and now looking at the fronts, currently 235's.
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.
Suggestion
I would be researching the rolling diameters for the sizes you're talking about, start with the OEM sizes, then check the variance between those, once you get that established, check the variance in the 245 F/ 305 R combo, if its the same variance, it is probably not an issue.
Leading evidence: 'Install michelin ps 4's' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check variance between those, once you get' (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.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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.
Suggestion
I would be researching the rolling diameters for the sizes you're talking about, start with the OEM sizes, then check the variance between those, once you get that established, check the variance in the 245 F/ 305 R combo, if its the same variance, it is probably not an issue.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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.
Suggestion · Original poster
Unless someone categorically tells me they run 245's and it works, then 235's it will be.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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.
Suggestion · Original poster
The trouble is I can't find any flavour of 997 spec that puts a 245 on the front, plenty that run with 305's matched to 235's which include the GT3.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
Check variance between those, once you get
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
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.
Suggestion
I would be researching the rolling diameters for the sizes you're talking about, start with the OEM sizes, then check the variance between those, once you get that established, check the variance in the 245 F/ 305 R combo, if its the same variance, it is probably not an issue.
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.
12 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Porsche Forum Australia: 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: 20261027T000231Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Long story short, where talking about a 997 S coupe. I have recently fitted Michelin PS 4's to the rear 305/30/19 and now looking at the fronts, currently 235's. My tyre guy is saying why don't you go for the 245/35/19 as according to him, match up better with the 305's. The trouble is I can't find any flavour of 997 spec that puts a 245 on the front, plenty that run with 305's matched to 235's which include the GT3. Pro's and con's please guys.
I'd also go with the 245s, you will get a little bit more front end grip, a little better braking and a little less understeer, but in the wet it probably wont help.
One thing I'd cautious of; given the same aspect ratio, the rolling diameter will be affected by this increased width... the ABS system in our cars can be very sensitive to differences in wheel speeds, the worse case is that it triggers ABS ice mode which dramatically impacts your stopping power in a normal situation (read almost non existent) needless to say the consequences can be severe or even deadly.
The key is to ensure consistent/relative rolling diameters front to back, I am not sure exactly what the tolerances are mind you. Rennlist search might yield an answer for you?
I would ask about to be honest and see if people are doing this successfully or not.
What Skidmarks said!
If you want to move your chassis grip around do it through sway bar settings. A 10mm wider front tire won’t instantly give you more bite
It's interesting, Rennlist is suggesting there are guy's that track there cars and prefer the 305/245 setup over 305/235. Regards the rolling diameters I think that is what my tyre guy was iluding to, the CS 2 spec is 295/235 and as I have gone with 305 rears(ticked off by PCM) his theory is it restores the status quo. Can I say upfront, this for me is more about aesthtic's not about performance gains. Having said that I'm also not looking to send the car backwards.
I agree
I would be researching the rolling diameters for the sizes you're talking about, start with the OEM sizes, then check the variance between those, once you get that established, check the variance in the 245 F/ 305 R combo, if its the same variance, it is probably not an issue.
My comment isn't intended to be of the fear mongering kind, however just a consideration you should be aware of... you can trigger the ABS ice mode driving the car on its limits just by your braking technique... even when the tyre sizes are fine. So it is plausible you may have no issues in doing it for 99% of your driving, but you might find out when its too late what ice mode is... ask me how I know
All makes sense Edgy
I considered going from 295/30/20 to 305/30/20 on my GT4 as I wanted to go to PS4 but they had to be "N" rated for extended warranty, 295 4S don't come in N rating, next best fit was 305.
Karl from Motorsport Dept PCM said Jim Richards GT4 on 305's got an error code at high speeds, so in the end I went with std CUP2.
For what its worth, I was looking at a 997 GT2 RS today, that runs a 245/35 19 front tyre, and they put that little fender flare on mind you, but the rear tyre is a 325/30/ 19 NOT a 305
The 2RS runs the same spec as the 7/2 on the rear but a wider front (245 v 235)
To confuse matters I had to stick a 245/40/18 on my 6TT at Bathurst this year when the Cup2 235 started to delaminate and we couldn't get a replacement in same size at the track (on the Easter long weekend). It ran fine for the remaining sessions on the weekend matched to a 295/30 rear.
This is a source reference. Confirm exact model applicability in the original material.
