When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
If I use the widest front tire size which fits within the stock wheel opening, and the car tends towards understeer, wouldn't the rear tire width be limited to the widest tires that would compliment the fronts without creating even more understeer, and not by the additional clearance provided by the rear flares?
If this is the case, then the flares serve no real purpose and are for show only. Tell me it ain't so.
Porsche added the rear flares, and fitted 255 rear tires. Pretty pointless since the original body style will accommodate up to 295.
It is not just a question of whether it will fit, it is also a matter of "where it fits". The GTS has a wider track given it sits on a 38mm spacer. Whether it needs it or does anything to enhance performance I have no position on.
Thus when running my current wheels that were on my late S4 I used the same size rubber but they sit 24mm further out each side- roughly a 2 inch increase in wheel track.
Interestingly I do have a bit of a problem getting the car off the line but I have a feeling that is because I am running too much camber at minus 2 degrees- until the bends start that is!
Fred brings up an interesting tangent point-- modern tires really like more [negative] camber, which offers some extra room at the top for a wider tire section. Consider that as you are choosing fitments that are right at the verge of fender lip contact.
....If this is the case, then the flares serve no real purpose and are for show only. Tell me it ain't so.
Bingo we have a winner !!!! the flares were no doubt added by the MARKETING department....
Flares indicate a flaw in the design of the car BUT BIG BUT they became considered a "performance" look. One need only look at the 996 which was slab sided to see how quickly demand can make a company add flares to sell cars....
Some times I miss Ed Ruiz and his personal favorite discussion topic of the contact patch !! He was however correct about the fact that you can make the patch longer or wider but not BOTH ! Wide tires corner better but a longer contact patch accelerates better like many things it is always a compromise....
And as far as understeering is concerned it is usually simple to control with proper turn in and using the loud pedal to rotate the rear end a bit.....
If I use the widest front tire size which fits within the stock wheel opening, and the car tends towards understeer, wouldn't the rear tire width be limited to the widest tires that would compliment the fronts without creating even more understeer, and not by the additional clearance provided by the rear flares?
If this is the case, then the flares serve no real purpose and are for show only. Tell me it ain't so.
That sounds right to me. On my 89 GT which sees occasional track use, I found that 235F & 255R on 8" & 9" rims respectively provide the most neutral handling. I tried running 285s on the rear at one time on a different set of rims, but it only created more understeer with no appreciable difference in lap times. I suspect a stiffer rear sway bar might have helped somewhat, but I never got around to getting one and instead went back to using 255s on the rear.
Setting up these cars to improve handling is not just about fitting wider rubber. It is doubtless the most important single element but by no means the end of the story. Once you start puling ore lateral G's things start bending more and these factors need to be considered.
Going from 225 up front to 235 is not a huge game changer but going to 265 is. Once you are into lateral G of about 1.2 you need more camber, if you want a decent turn in you need less toe, less toe creates twitchy behaviour so a bit more caster helps. The car will drive out of a bend quicker with a bit less rear toe but reduce it too much and you get no bite. With every adjustable parameter there are inevitably pro's & cons. More camber gives better cornering but less braking grip- it is all a question of balance. I had a lot of advice on these parameters and had quite a few iterations of alignment to get the handling to where I wanted it to be.
The track experts will porbably tell you that you also need to optimise for different track configurations. Nascar machines are a bag of crap in a straight line but man do they go round left hand bends- "horses for courses".
I ran with rubber slightly wider than stock before fitting wider wheels- both work fine but the wider wheels put a bigger grin on your face when hounding 911's.
On stock 17" Cup 1's I have I have 235/45s on the front and 285/40s on the back - thats about as big as you can go on the stock rims due to bead width. However there is a lot of room at the back for a wider tire with few issues except getting the correct offset/spacers. I think up to about 320 looks very doable. The front is tighter if you want no rubbing I think 235 is close to the limit without different offsets, not even sure if that will gain much.
I think I'd have to go to wider 18" rims to have much real choice on wider rears.
My 1991 XX8 factory wide body GT is running the factory original D 90's - 7.5 x 16's with 225's on the front and 9 x 16's with 245's on the rear.
The factory filled out the rear quarters with 43 mm spacers and when viewed from behind - looks like it is on bicycle tires next to my 1990 GT outlaw that has cup 4's shod with 245 35's on 8 x 18's in the front and 295 30's on 10 x 18's on the rear. The wide track and originality are totally cool though...
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
03-18-2015, 10:10 AM
George Layton March 2014