13 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHDoes the tire size/diameter for a C4
Leading reported evidence
Recommend 30 series tire
Suggestion or failed attempt
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 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
Is there a specific reason that you recommend the 30 series tire for the rear?
Leading evidence: 'Recommend 30 series tire' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Recommend 30 series tire' (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 · Original poster
So, if I go with a 295/30 (Tire shows Revs Per Mile is 832 and 25.0 Dia) for the #1 example, the difference between front and rear rotations only changes by 1 RPM, from 23 Revs Per mile to 24.
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
If those numbers don't have to match or be really close on my C4 (need a definition of "real close"), I will change things up.
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
I am planning to run 225/45 up front and a 285/35 in the rear.
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.
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
So, if I go with a 295/30 (Tire shows Revs Per Mile is 832 and 25.0 Dia) for the #1 example, the difference between front and rear rotations only changes by 1 RPM, from 23 Revs Per mile to 24.
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: 20261026T155324Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Ok, I just got a deal on a set of BBS "lightweight" Porsche wheels (996362), 18" x 8" and 10". I am checking out tires and I noticed a lot of difference in Overall Diameter and Rev's Per Mile, even for the same size of tires but from different manufactures. Since I have a 2001 C4 Triptronic, so how much difference in those numbers, if any, from from front to rear is acceptable? I don't want to muck up the drivetrain.
I am planning to run 225/45 up front and a 285/35 in the rear. The differences in Dia and Revs Per Mile are, front to rear - Dia, 2.6/25.9 and Revs Per Mile, 800/803 for my current tire choice. I have looked at difference combinations with as much as .7" diameter differences and 35 Revs per mile differences. What differences in those numbers, front to rear, will cause issues?
I was looking more at overall tire diameter and rev's per mile for each size. That is why I asked the question. I don't have a lot of knowledge about the all wheel drive system in these cars and how a different sized tire from front to rear would affect the drivetrain. If those numbers don't have to match or be really close on my C4 (need a definition of "real close"), I will change things up.
Ideally, you want your front tires to be slightly taller than the rears (like 1% rolling difference or so). The size difference is intended to put a little bit of drag on the viscous coupling so that it send some power to the front wheels to help "pull" the car. If you go the other way around (rear tires slightly taller) it's not going to hurt anything, but it will theoretically cause some drag on the drivetrain because the car is now "pushing" against the viscous coupling.
You should be looking at 225/40/18 and 285/30/18 with the size wheels you have. Another option is 235/40/18 in the front and 295/30/18 in the rear if you want a meatier look.
You want them as close as you can get, the viscous coupler that is used for the awd system won�t like big discrepancies and will get hot if they are different. It�s not a rebuildable part and is sort of costly.
I like the "meatier" look, but will 235/40's fit nicely on 8" fronts and will 295/30's fit well on the 10" rears?
This is an example of a tire spec of some combo's I am looking at. Are these two pairs good to go?
1. 235/40 front is 818 Revs Per Mile, dia is 25.4" - 295/35 rear is 795 and 26.1"
2. 225/40 front is 828 Revs Per Mile, dia is 25.1" - 285/35 rear is 803 and 25.9"
I will also be looking at other tire combos. I am just trying to learn and ballpark what is good and what is bad and what works and what doesn't.
So, if I go with a 295/30 (Tire shows Revs Per Mile is 832 and 25.0 Dia) for the #1 example, the difference between front and rear rotations only changes by 1 RPM, from 23 Revs Per mile to 24. Is there a specific reason that you recommend the 30 series tire for the rear?
1. 235/40 front is 818 Revs Per Mile, dia is 25.4" - 295/35 rear is 795 and 26.1"
2. 225/40 front is 828 Revs Per Mile, dia is 25.1" - 285/35 rear is 803 and 25.9"
Again, just trying to learn more about the car and it's needs. Oh, and I don't mind a little sidewall between rim and road. I'm not tracking it.
