Robby

I'm toying w/the idea, since I'm trying to upgrade to larger wheels- this would help fill out the rear fender area w/a slightly larger RD yet STILL give slightly shorter profile- woud LOVE to go to 18's, but, the extra weight, plus, I would want at leasat 275/35/18's- this would give a profile of 96.25 & RD of 25.58"- this profile is HAIR short for street, IMO, but, I could live w/it- the RD would be GREAT, BUT, I doubt it would fit correctly- any input?

Those who have run w/265/40/17's in rear instead of 255/40/17's- how was the overall handling, etc, affected? I like the RD, but, not so much the profile- 255/40 is 102mm & 265/40 is 106mm- the extra RD would go from 25.03 to 25.35. STOCK is 24.68 & 24.86 (Turbo S/Turbo), so, the 255/40/17 would STILL be better in both ways, but...

Thanks a lot,
Robby

trebor_quitman

I've only driven them from my house to work so far, so I'm still getting used to them. But I Went from 16's/205&255's to 17's/205&275's. Seems ok, it just tracks a bit wider/understeers a tiny bit more than I'm used to, but I think it's because the front's are only 205's. I posted a thread about it, 265's shouldn't be to bad if I'm running 275's and not seeing any severe issues. But like I said, only a few miles/minutes on my new setup.

Robby

Roberto-
So you're running a 40% profile- 275/40/17? Wow, IF so, that's even taller- 110mm- almost a PERFECT full inch over stock RD- 25.66"- IF that would work, then, a 275/35/18 MIGHT work- 25.58"- I would LOVE to be able to squeeze a 285/35/18, but SERIOUSLY doubt it would fit- 25.85"- I'm thinking the 275/35 would be a stretch, but... Thanks for the reply- please let me know after you've driven it for awhile- otherwise though- could you be running a 275/35/17? THAT would be a COMPLETELY different thing altogether...

trebor_quitman

I threw her into some nice hard lefts and rights with some reasonable stop and go aggression on the way home from work. The fronts are 205/45/17's and the rears are infact 275/40/17's(had to check). No rubbing, but it sure fills out the hole. I'm running on shot stock rear shocks. It should handle nicely when I get around to putting on the yellow konis. Now to save up and get the thing that caused me to go to a 17. Big reds. I wonder if paragon takes penny rolls.

PorscheG96

Robby you're right, the 275/40-17 is about 1 entire inch taller than original tire sizes 205/55-16 and 225/50-16. Standard 17" tire sizes for 968, etc are 225/45 and 255/40...therefore it seems like 235/45 and 265/40 should work and only be marginally taller but slightly wider as well. I've considered this as tire brands like the S-03 and others offer 265/40 rear tire size in 17".

If you go 18" then you'll want 265/35 or 285/30...back to 17" though, I realized about 2 years ago that 275/35-17 would be an excellent rear tire size to have, so I talked to Kumho and Yokohama [seems they'd be the most willing] about producing the tire because NOBODY makes that size.

They appreciated my inquiry and I was working at America's Tire Co. at the time, but they could not justify development of a tire that sells so few units per year. To make it work they would have to charge ~$1k per tire which is unreasonable, therefore we stick with tire sizes that are nearly always Porsche OEM.

josephsc

Wow, and at the same time, the fronts are only 24.26" tall. I couldn't find your old thread, but would love to hear more.

BTW, I noticed your S3 designation -- what's the story behind it?

trebor_quitman

The "944S3" designation was what the 968 was called in plant, I have 968 engine 6 speed and suspension/brake setup on my 88 n/a. Not for much longer though!! I just had a set of big red calipers fall in my lap for 200 bucks!! I was expecting to have the parts to do that maybee a year off, but I guess it's closer!! It's all coming together so quickly.

josephsc

nice! I just got a 968 engine for my 944 N/E -- which is my own designation for what used to be a 944 N/A. I'm keeping the tranny, but I did get 17" wheels just in case big reds come falling on my laps too! She's not quite road-worthy yet, but so close!

Robby

Thanks for the input everyone...

Trevor- the 275/35/17 sounds cool, but, that would void MY reason for wanting different sizes- I'm wanting to fill up the rear wheel well- I LOVE the way these cars look, but, the rear well looks ugly IMO- something's just not quite right- more noticeable at certain angles- I put 1/8" spacers on the rear of my Turbo S- helped SLIGHTLY- 1/8" just isn't very much- the wheels (w/thier RD) just sort of get lost in there- ANOTHER part of the prob is the door gaurds- they form a line w/the line coming off the rear bumper & from the door (usually covered by door gaurds on 951's)- also, the SHAPE of the rear wheel well vs the shape of the FRONT wheel well, PLUS, the fact that the FRONT wheel is slightly larger- even w/regular turbo sizes- the following is a chart of sizes (for everyone's benefit, as I'm sure you're well aware of how to get the #'s...)- the first # is the tire size, followed by profile & then RD- & then the problem...

205/55/16 - 112.75mm - 24.88"
225/50/16 - 112.5mm - 24.86"
245/45/16 - 110.25mm - 24.68"
------------------------------------------------------------------------------------------------
225/45/17 - 101.25mm - 24.97"
255/40/17 - 102mm - 25.03" - profile's perfect, but RD's not much larger
265/40/17 - 106mm - 25.35" - profile a TAD high, but RD's getting ~right
275/40/17 - 110mm - 25.66" - profile too high- RD would be great
275/35/17 - 96.25mm - 24.58" - profile too short- RD too short
285/35/17 - 99.75mm - 24.85" - profile ~perfect- RD too short
295/35/17 - 103.25mm - 25.13" - profile ~perfect- RD acceptable
------------------------------------------------------------------------------------------------
265/35/18 - 92.75mm - 25.30" - profile too short- RD pretty nice
275/35/18 - 96.25mm - 25.58" - profile a hair too short- RD excellent
285/35/18 - 99.75mm - 25.85" - profile ~perfect- RD may be too large(?)
285/30/18 - 85.5mm - 24.73" - yeah, right...

ANOTHER problem(?)- these cars have always had slightly taller front wheels/RD/profile's than the rear- would changing this ratio make any dif in handling? If I went to a 225/45/17 front & 265/40/17 rear, then I'd be going from having the front be 2.25mm taller profile & 4.5mm taller RD to the REAR being 4.75mm taller profile & 9.5mm taller RD...


You see, I want a lower than stock profile- ~102mm being perfect, but no less than ~99mm or more than 106mm- the RD needs to be at LEAST 25.03"- would prefer ~25.5" for the rear- NOT for the front- I've even toyed w/the idea of using 18's on the rear & 17's up front- say...275/35/18 rears & 245/40/17's up front- I think this would LOOK about perfect, IF I could find matching factory wheels- of course this is impossible & I'm not at all sure how it would actually FEEL, etc...

Roberto- do you have any pictures of your car? Would LOVE to see a side view...

Robby

I JUST noticed this quote- THAT means that YOU ARE running taller rears than fronts, which is the OPPOSITE of what these cars had originally- that IS very interesting- WHY did you pick such a unique size configuration? Those really aren't even close- were YOU looking at it from a LOOKS perspective, like I'm asking about & just decided to roll the dice? going slighlty larger in rear & slightly SMALLER up front, like you did, SHOULD help tremendously- please let me know more as you get used to drving w/them like that...

Thanks a lot,
Robby

trebor_quitman

Noticed some mild rubbing today on the 275's while exiting a down sloped driveway. The force of the car coming down the hill, and the wheels coming up the dip must have overpowered the shot shocks.

Robby

Thanks for the info Roberto- do you have any pics of these? I'd love to see some...

trebor_quitman

My cheepo digi took a turn for the worst, Will try to borrow one of my roomates cams. One of my roomates, He posts here and on the turbo board as Redeye, might take a few pics for me if he's not to busy trying to finish his 951 oil pan gasket / new turbo project. I think he ran into some badluck, wish I could have been there to help but I hadta work. I've been so busy trying to get my girlfriends FWD Auto VW Cab out of the garage. I found a half inch thick sludge of metal shavings and needle bearings lining the bottom of her diff case!! CORE!! It's all good now. FINALLY I can start to work on my car again.

C5Driver951

On your turbo S you can run up to a 305 section width using the correct tires and some massaging. I've seen a 315 on the back of a stock bodied 951 at the track, but I'm fairly certain his car was VERY stiff. Needless to say he had custom wheels with the perfect offset.

I used to run 255/40-17s on the front and 275/40-17s on the rear of my car at the track. I had NO rubbing issues, and the gearing difference really didn't bother me. In order to do this correctly you need at least 8.5 and 10 inch rims.

Performance wise I really think the best set up right now is a 285/30-18 on the rear and a 265/35-18 up front.

Of course for a street car a set of factory cup1s with 205/50 and 255/40-17s look just right...

Robby

I couldn't imagine going to the 305 & up stuff, mostly b/c of COST Yes, mine is a street car too... I've heard of peopel getting away w/315's too- that's the largest I've heard...IF I went w/18's, I would definately not go w/a 30 aspect ratio, as that would be too low profile & wouldn't fill out the wheel wells like I want- I would TRY to get 27/35/18's under there, but am not sure it would work- I doubt I'll have the option to get 18's anyway- the only ones I would REALLY want are hollow spokes & even THOSE come back to the extra weight stuff I'm TRYING to avoid- 17" 993's are a HAIR lighter than my 16" CS's...

275/40/17 needing 10's? I know it would be better, but, remember, the Turbo S had 225/50/16's on 7" fronts & does fine- so, by THAT comparison, 275's would work just as well on 9's- I mean, 275mm is 46.4mm more than 9" & 225mm is 47.2mm more than 7", so it shouldn't be a prob- of course, I realize that more rim under the tire helps stability- of course, you have to factor in the negatives of the extra weight, etc vs what it all actually accomplishes, vs being a street car, etc...

205/50/17's up front? No way I'd do that- I'd never go <225 on fronts- several people have commented on the lack of braking traction,etc- SOME have even suggested getting 255/40/17 on 17x9's all the way around(!?) but I'm not sure I'd like this- they say turn-in is incredible though- you have to remember that the Turbo S came w/225/50/16 (on 16x7's) & 245/45/16's (on 16x9's)- the 968 M030 did the best thing really- the Turbo S's 245 is a little narrow for the 9" rear & the front 225 could use a TINY bit more rim underneath, so, the 968M030 used 225/45/17's on 17x7.5's & 255/40/17's on 17x9's... - balanced out nicely- of course, then they went & RUINED the gearing(!?!?!?).

I really wanted 17" C2 wheels, like M030 968, but, they're heavier, so, I'm looking for 17" 993's (later 968's had these) but doubt I'll be able to find the 7.5" front- since the front really isn't as big of a prob for me (it's the REAR I want to fill out)- I'll probably get some 993's when I find them, regardless of 7" or 7.5" fronts- if 7's, I'll be happy w/the slightly lighter weight & if 7.5's, I'll be happy for the extra width- IF 7.5, I MIGHT go w/235/45/17's & 265/40/17 rears??? SO MANY OPTIONS.....