worf928

You are missing Kibort's point: The 928 is under-tired for its weight relative to other sports/GT cars. Case in point: my wifes C5 Z06 (front v8, rear transaxle) weighs in a bit less than a 928 and runs 265/295 stock.

dprantl

If someone made some Carrera III replicas in 9.5" with a 70mm offset for under $1000 you could run 265-35/18 on all four corners. I really think that a lot of people would buy them.

Dan
'91 928GT S/C 475hp/460lb.ft

RyanPerrella

I get the point but the fact is that porsche doesnt make a wheel that will work.

The Carrera Sport wheels i had were 9.5" wide and i had 245 on the front but they rubbed and the car tramlined allot. I went down to 235's and it was much better (like the first set of 19's i had)

Short of custom wheels which are $4K plus your not going to be able to find a 10" wide wheel with the correct offset where you can fit that kinda rubber. Personally I like allot of the Porsche wheel patterns and they are readily available so they are much cheaper, because of that i cant ever imagine going to some $4K plus wheels and possibly compromise on the styling just to have this, but thats just me. I imagine i am in the vast majority on this point though too.

I guess if you want neutral handling, you need to equalize the grip at both ends, 275 all round should get you there, but then everyone wants the staggered setup so you will likely compromise.

mark kibort

better to put that slightly larger tire in the rear, like a 275 or 285 for a street set up on 9.5"rims.

worf928

B.S. You can get forged 18" wheels with the right offsets for less than $3k. It's been done and posted here. 3-piece forged wheels with the right offsets in 17" are less than $3k. You can spend as much as you want to on wheels. But, you do not have to empty the college fund to get good wide wheels with the correct offsets.


You can run 9" or 9.5" in the front with no problem and with that wheel you can get 265 in the front which is plenty of tire.

Show. Or go. Your choice. But, Fikse and CCW make some nice looking wheels that are well below $4k a set as long as you stay in the 17" to 18" sizes with 9's and 10's. I personally don't like any of the new Porsche wheels.

worf928

Make that $2600 for CCW 18" wheels:

https://rennlist.com/forums/928-foru...se-wheels.html

IcemanG17

Hmm....40-44psi hot is quite high.....I like to keep my R888's around 37-8 front and 36-7 rear....granted they are 295 front-335 rear..but that seems to be a nice zone for them where I'm getting full tread use and good feel...If I go higher...then the tread starts to narrow A LOT....

IcemanG17

I run C10's 18x10 & 18x12 on the widow...great wheels

RKD in OKC

Oh My. I just must not be serious enough, I don't want to go shopping for wheels again.

My BMW X3 runs 245/255 Pirelli Rossos, and I have set FTD with it. No idea what the rim widths are but they are 19 inch.

mark kibort

speaking of pressures. you never got the tires set at 30psi cold?? When the pros were running on street tires,280treadwear, thats about where they started.

jorj7

RDK,

I never do any serious driving on my PS2s until I have over 200 miles on them, 400 is better.
They are very slippery when new. Also I usually run them at a lot lower pressure then any
other tires I've used. I start at 37 psi and go down depending on the conditions. 40 psi was
too much for me to feel confortable with them. I also run a 235 in front, but for Open Road
Racing wider isn't alway better. For the track I'd suggest wider.

dprantl

Lol, it's interesting that is exactly the number I came up with after years of street experimenting.

Dan
'91 928GT S/C 475hp/460lb.ft

mark kibort

that is a good point, however, the T1S was supposed to gain .5 seconds when they were new, thats why all the speedGT guys were tossing them in the trash can. I grabbed a few sets during those 2 years they used them. Lets face it, they were garbage for the track, compared to a R compound, but they were somewhat predictable and sure did last a long time! I wish I would have grabbed a few of the touring car sets 235x17s for my street BMW.

RKD in OKC

I understand wider is better for a heavier car. I just don't like the current tire choices in wider tires. Tire choice is the main reason I went to the 18 inch rims over the stock 17s.

At our events and many others these Dunlop Direnza Sport Z1 Star Spec with a 200 Treadwear rating are matching times with R compound Hoosiers. For 18 they come 225, 235, 245, 255, 265, and 275.

The contact area of these tires after the event are noticeably rough like R compound tires. The closest I have to compare the roughness of the tire is that it looks like my old Goodyear R1s used to.

So far these tires are seriously sticky in a straight line. I cannot spin the rears in first with throttle and I could spin the PSs in 2nd. Instead of the usual lift on throttle to prevent tire spin, it just bogs a little and goes. And I never got into ABS under braking where I did occasionally with the PS. Especially at the end of our 100 mph straights. Besides the tires I also put in a 5/55 bias valve and went to some EBC Yellow Stuff pads.

Like I said before, since my GTS was fairly well balanced with only slight understeer running 225F/285R Pilot Sport Ribs I thought 235F/265R would put it pretty much spot on as long as I was running the same brand/tire all the way round.

Reason so far for understeer/slower lap times with sticker tires and wider fronts.
1. New tires too sticky, more friction and make car slower.
2. Dampers not tuned for sticker tires causing front end lift on throttle application.
3. New tires not scrubbed in well enough, give it some time.
4.. 2 and 3 above.

RyanPerrella

I ran 245 35 19's on a 9.5" rim with 55mm offsets which is the only offset porsche has for that wide a front rim.

The 245 rubbed on the front spoiler and on the area behind the tire where the plastic moulding attaches at the bottom of the aluminum fender. Switching to 235 cured this rubbing issue and the tramlining

sorry not sure how in the hell you would get 265 on that Porsche wheel and not have the problem be even worse.

As for wheel prices, $4K - 3K same difference, Porsche 19" wheels can be had for a grand, not 4 and not 3. As for looks, yeah they should look good, those CCW's look like anything you would find on any import, sorry no centercap, not my style nor would i ever pay $3k for those. Yeah wheels are about the most personal thing you can easily do to a car, but dont tell me its BS. Ive tried, with porsche wheels, the fact of the matter is that with 996 997 wheel offsets they are close, but not ideal. Nor does porsche really have a good 10" wheel for the front, so on the porsche wheel front, we are limited.

The Panamera may change this problem, new chassis, new wheels, new offsets, perhaps they are more compatible with the 928's offset needs, but ive still never seen specs on these wheels and wont know until the car is in the showroom.

Or, you could possibly invest in a nice set of wheels and try having the wheel widened, not sure how safe this would be, not do i have any idea what it would cost, but that maybe the ideal solution without having to spend $1,000 per corner per wheel.