315 - 30 rear and 245 - 40 front

[cgfen]

yes
i know this has been discussed a few times, but now MY car's sheetmetal is at stake
and the board is a little slow right now.


http://forums.rennlist.com/rennforum...15-18s-ok.html

http://forums.rennlist.com/rennforum...-on-933tt.html

http://forums.rennlist.com/rennforum...for-993tt.html



i recently scored, (thanks Chris Walrod), a set of 996 TT wheels shod with NT01s;
315 - 30 X 18 rear
245 - 40 X 18 front

i've done a test fit and a mellow drive with no contact, but man, the minimal clearance between the tire and the inner lip of the sheetmetal is close close close.
no issues if i drive over a smooth road, but a "big" bump and some steering angle cranked in looks spooky.

my car has -2 degrees camber front and rear.
wheels are 996 TT
ride height = RS +10mm
96 C4S
Car is currently RWD only after AWDectomey, so diameters are not critical

anyone running something very similar with good success?
good success = no rubber to metal contact.

Thanks

Craig

hmmmmmmmm none of the links seem to be working right now?????????
i'll try to sort it out

[911/Q45]

I've run those wheels with 235/40 and 315/30 for a long time with no problems. Much track use and no rubbing from any of several brands of tires. The camber goes more negative as the suspension compresses, so bumps shouldn't be a problem.

[Tour18]

I'm about to put a 315s on mine. I have made a zillion measurements. The 315s just aren't that much bigger...

[Greg H.]

I run those tires and rims with -1.9 negative at about Row030 ride height with no problems at all.

Greg H.

[cgfen]

Originally Posted by 911/Q45

I've run those wheels with 235/40 and 315/30 for a long time with no problems. Much track use and no rubbing from any of several brands of tires. The camber goes more negative as the suspension compresses, so bumps shouldn't be a problem.

Originally Posted by Tour18

I'm about to put a 315s on mine. I have made a zillion measurements. The 315s just aren't that much bigger...

bigger than what?
I've run as large as 295 - 35 with no issues.
295s are ~ 0.5" taller and 0.75" more narrow than the 315's.

Originally Posted by Greg H.

I run those tires and rims with -1.9 negative at about Row030 ride height with no problems at all.

Greg H.

thanks for taking the time to comment guys, i'll let you know how it goes.

Craig

[JJayB]

I've run 315 with no problem. You may get inside wheel rub with the 245x40's on full steering lock.

[Tuner1]

On the rear fitting the 315/30-18 is easy.

For me the big issue is tire vs wheel width. I would not run larger than a 305mm tire on an 11" wheel (Porsche uses 305/12" for 997 and 315/12" for 996).

Same goes for the front. I would not run wider than a 235/40-18 on an 18x8" wheel. Using a 245/40-18 on an 8" wheel really compromises the profile of the tire...IMHO, YMMV

FYI, this advice is also based off the wisdom passed onto me by a wise racer/engineer at Michelin

[pstoppani]

I have 315s on 11" wheels and they work great, and 11" wheels are well within the spec for those tires.

[Tuner1]

Originally Posted by pstoppani

I have 315s on 11" wheels and they work great, and 11" wheels are well within the spec for those tires.

"Within spec" for sure but not ideal for maximium performance applications.

Of all the tire engineers I have asked (yes I actually go out of my way to track these guys down) every single one of them has strongly suggested wide wheel/narrow tire is superior to narrow wheel/wide tire...within their given specs range.

Like I said, YMMV. On a stockish 993 with softish suspension it likely won't matter what you run

[Al Pettee]

Originally Posted by Tuner1

"Within spec" for sure but not ideal for maximium performance applications.

Of all the tire engineers I have asked (yes I actually go out of my way to track these guys down) every single one of them has strongly suggested wide wheel/narrow tire is superior to narrow wheel/wide tire...within their given specs range.

Like I said, YMMV. On a stockish 993 with softish suspension it likely won't matter what you run

Agree 100%.

Just because the tires fit on those rims doesn't mean they'll perform any better-indeed, with the extra tire sidewall from tire bulge, one is likely to experience "wobble" especially in turns. If you want bigger and wider tires, then get bigger and wider rims first.

This thread is kind of like those bench racing arguments:

"Oh yeah, well my Corvette has 3000hp so it has to be faster than your Corvette that has only 2000hp."

[pstoppani]

I didn't get the impression the OP was looking to set any world records where that last millisecond of performance was a requirement...

[Tuner1]

Originally Posted by pstoppani

I didn't get the impression the OP was looking to set any world records where that last millisecond of performance was a requirement...

All the more reason to stick with OEM size tires

The 993 GT2 used 18x9" with 235/40 and 18x11" with 285/35!

Taken from the first link posted by the OP:

Jean: A 245 on an 8" wheel is not recommended if you choose to go this route..

jrgordonsenior: I ended up with 265/315 MPSC's on 9-1/2 & 11-1/2 rims after testing many different combinations.

Regardless, I am far more OCD when it comes to rubber than most people could ever imagine. Unless my advice is requested I will bow out of this thread

[Greg H.]

If I only have an 8" front rim, are you saying my car will understeer less with a 225 than a 245?

Greg H.

[canysmc]

Originally Posted by Greg H.

If I only have an 8" front rim, are you saying my car will understeer less with a 225 than a 245?

Greg H.

with a 295, 305 or 315 rear?

[Spartan]

Should fit just fine, used to run that combo when I had tiny fenders

I highly suggest 275f and 335r but some slight modifications might be in order