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.
Amazing information here.
Some of guys are a wonder to this from. I totally appreciate the input.
im going for a new set of RE71Rs in 18 MY02 wheels
235/40/18 upfront. I had understeer I can live with a tiny oversteer.
275/35/18 in the rears. I was afraid I might run with 285s in the back.
I also have a 17 Cup2 wheels
Nitto NT01s
225/40/17 upfront
255/40/17 in the rears.
This is I think the perfect setup
How much air would be optimal for these tires?
32 or 34 all around?
Check the circumference of the 18" sizes. They are too tall. I would not mess with it personally. Been there done that including running a 245 upfront when racing. 225/18 and 265/18 rear is perfect IMO. for 17's stock yes, perfection lies with 225front and 255 rear. My first ever PCA race was on 17;'s!!!
IMO suspension setup, camber etc is where the magic is....
For street setup pressures 34 front, 36 rear. Track on streets, my old notes say start cold 27psi front 28 rear ending up at 34 front 36 rear when hot.
Here is 2 comparisons
upper Speedline 8 & 10 225/40 & 265/35 to 8.5 & 10 Forgeline 23540 & 275/35
all 3 it fine on a very low 993 n/b
lower is the same Speedline and the same Forgeline wheels w/ 245/35 & 285/30
main points
the taller 235/275 cost ~3.6lb-ft this is enough to barely feel and move shift points on a track, at LRB the neet gearig is awkward and WGI and Monticello it's great
the shorter 245/280 gain ~6.3lb-ft, again noticeable and moves shift points the other way, great for all 3 tracks
Have Cup2's with RE71R - 225/45 and 255/40 - Can I get the 235/45 on the front, but Im maxed out on the back, as they don't make anything wider for 17...
Have a set of MY02 with garbage on them, and was thinking of getting RE71R's for them, as I need new rubber anyway.
Just installed PSS10 all around and a TBD from Guard.
I know that for AX, you want as wide as possible upfront.
I have been EATING my rear sidewalls for the past couple of seasons, and the latest set I got in Sept, had no side walls after 3 events. This was after the TBD install, but before I replaced the PSS9's with PSS10's. I've had 2 events after the PSS10's, but still think I am killing the sidewalls.
Would a wider tire in the rear, on 18's help with that?
My other thought is to just get a fresh set for the Cup2's and drive another season and see what happens with the sidewalls, etc..
Have Cup2's with RE71R - 225/45 and 255/40 - Can I get the 235/45 on the front, but Im maxed out on the back, as they don't make anything wider for 17...
Have a set of MY02 with garbage on them, and was thinking of getting RE71R's for them, as I need new rubber anyway.
Just installed PSS10 all around and a TBD from Guard.
I know that for AX, you want as wide as possible upfront.
I have been EATING my rear sidewalls for the past couple of seasons, and the latest set I got in Sept, had no side walls after 3 events. This was after the TBD install, but before I replaced the PSS9's with PSS10's. I've had 2 events after the PSS10's, but still think I am killing the sidewalls.
Would a wider tire in the rear, on 18's help with that?
My other thought is to just get a fresh set for the Cup2's and drive another season and see what happens with the sidewalls, etc..
For A/X you want the car to rotate more easily than for track use, so many run a more square setup and or make big changes in springs and roll bars to stiffen the rear wrt the front
Hard to say what is causing the tires to eat sidewalls, One possible explanation is too little camber. The faster you go and the gripper the tires the more the tire camber tends to go positive, this is bad for grip and wear
I like My 02 8ET50 and 10 ET65 a lot, they very light, for road or track use 225/40 & 265/35 are good sizes , for A/X go w/ maybe 235/40 and 265/35 x18 and install adjustable sways from an RS
As I posted above taller tires, particularly the drive tires incur increasingly steep inertial and gearing penalties
WIDER FRONT WHEELS ON A 993? How will this affect handling? Before I buy two more sets of rubber!
Question # 3: has anyone tried INSTALLING an OEM P car Rear 8.5x17 width On the Front of a 993?
996 Carrera 2 or Boxster 987 - 8.5 inch ET50
With the stock tire size if I understand correctly using 205/50 17 on 7 inch front with 255/40-17 on 9 inch rears = lots of understeer.
The Recommended size using 7 inch front cup II wheels to reduce understeer is install a 225/45 – 17 tire.
Tire rack states a Michelin 4S 225/45-17 requires a minimum 7 inch width to max 8.5 inch wide wheel.
Based upon a (Bill V) recommendation of widest wheel and skinniest tire to improve turn in, I am thinking buy or install 8.5x17 oem wheel and go with 225/45 tire width and largest rear on 9 inch for more bite say 275/40 instead of 255/40-17
So, in conclusion, if you agree with the 8.5 front? should I go one up again for balance/turn-in with a 235/45 front with 275/40 rear for DE?
Thanks for reading
I guess the OP is long gone, but
I run several sets of wheels and one of my favorites is 8.5J front (which is an OEM P-car rear) with 225/45/17 and 9J rear with 255/40/17. Ideal size for the front/225 would be an 8J, which I also have in a so-called Cup2, but I prefer the look of the BBS.
My 993 doesn't understeer anyway (not standard suspension) but the above setup gives a pleasing balance and lines up with the bodywork better than 7J 205s. I'm so vain, but the downside is that the 8.5J front isn't quite so telepathic as the factory 7J with 205 - gee it seems the 1990s engineers knew what they were talking about
Last edited by orangecurry; 11-24-2020 at 06:29 PM.
I run several sets of wheels and one of my favorites is 8.5J front (which is an OEM P-car rear) with 225/45/17 and 9J rear with 255/40/17. Ideal size for the front/225 would be an 8J, which I also have in a so-called Cup2, but I prefer the look of the BBS.
My 993 doesn't understeer anyway (not standard suspension) but the above setup gives a pleasing balance and lines up with the bodywork better than 7J 205s. I'm so vain, but the downside is that the 8.5J front isn't quite so telepathic as the factory 7J with 205 - gee it seems the 1990s engineers knew what they were talking about
Ideal size for the front/225 would be an 8J,
??
a 225/35 x17 performance tire wants a wheel 7.0" to 8.5" bead width, ideal for comfort is 7" as this lets the sidewalls roll around more freely, ideal for max performance is 8.5" as this limits sidewall flex, it's the analogous to using mono-***** instead of rubber bushes..
in the back for 255/40 x17 a similar situation exists, the tire wants an 8.5" to 10" bead width, 8.5 is best for comfort and 10 for performance
On my upcoming wheels I'll be running 18x8.5 ET 48.5 with 235/40/18 and 18x11 ET 38 with 295/30/18 on a widebody. RS spec suspension, alignment otherwise.
Just another data point. I'm not seeing understeer and the car feels nicely balanced on the street.
The fronts fit perfectly with no rubbing. I'm running 245/35-18 Bridgestone tires in the front with a tread width of 8.5", which is what allows me to fit 245's in the front. My car has PSS9 coilovers and has been lowered 20mm in the front. Tread width varies so much from tire to tire for the same size. I could also run Michelin 4S 245/35-18 tires (8.4"), but not Michelin Super Sports (9.2").
08-24-2020, 01:41 PM
)
