Skip

But of course... doesn't everyone?
http://www.ccwheel.com/

Skip

instigator

what is the biggest tires i can put on a set of aftermarket 993 17x7.5 & x9 in wheels for a 85.5 car

ian

To preserve balance run 225/45s up front and 255/40's in back.
It is a nice balanced set up and leaves you with a lot of tire options.

instigator

thanks Ian that sounds good

Doc

Skip,

You are correct, they are CCW... I didn't know John had an official site up and working. Last I saw, if you tried to get to his site.. you got some VERY INTERESTING looking uh erh.... let's just say there were some nice looking round things on his site. (I believe it was a screw by the guy who did his web site for him.. I think the web guy did mainly XXX sights.) ... anyhow

I went with the size I did based on John's personal reccomendation. It wasn't a cost issue, i.e., he didn't make any more money on the deal, the cost to me was the same regardless of the width.

John reccomended I go with the wider wheel because it would, "better square" the tire allowing for the widest possible contact patch for a 275/40/17. Also it does alow for me to go much wider should I choose to do so in the future.

I will tell you though, John doesn't usually do Porsche but he sure knew what he was doing, I have only a "cat hair" (that's the politacally correct way of saying it) of clearence both inside, outside and from the caliper. In fact when I first put them on, I thought they were too big... as it turns out they were not.

On last thing, John is a self proclaimed lover of, "knuckle dragger" cars as he calls them, or big block big HP cars. He's not to found of Porsche owners, so if you call him, be cool... he makes a great product at a great price, but he also does things at his own pace in his own way. And I get the feeling if he decided he didn't like you, he wouldn't take your business.

Other than that, if you manage to get along with him, he's a pretty funny guy.

Danno

There really isn't one "perfect" answer for rim-width. That's why the manufacturer always specifies a rim-width range. The specific width specified usually is a "measured rim" size. That is the tire's section-width measured on so-and-so sized rim, but that size isn't carved in stone or even recommended as "ideal", just happened to be what they measured the tire on. Each rim width within the range specified by the manufacturer has different handling characteristics, just choose the one you want. If you want maximum cornering grip and instantaneous response to steering inputs, then go with the widest width specified.
Yes, you betcha! Have to really do a before & after comparison to drive this point home. Most people haven't done this and there's no control reference for comparisons, just that "it seems to work OK", but compared to what? (could be better)

When I went from the stock 16x7/8" Fuchs on my 951 to 16x10.25" HRE-504 rims (with same 225/245 tires), I was astounded. I had swapped rims between run groups at Laguna Seca and on the next session out, I literally flew off the track on the INSIDE of turn-1. That's because the wider rims provided such quicker turn-in response that my usual steering inputs was more than necessary.

What happens when you turn the wheel is that the mass of the car wants to continue in a straight line. But tire tread is aimed towards the inside of the corner. This causes the sidewalls to be pulled laterally as the wheels and car proceed in a straight line (ever see a head-on shot of a car going into a corner?).

On stock sized rims and tires, the tread and sidewall will be pulled up to 3" laterally and only when this pull has reached it full extent, does the tire then start pulling on the rim edge, which then pulls the car sideways. This lateral displacement takes time and gives you the floppy sloppy turn-in you get when you fit too-wide of tire onto a narrow rim. This is also the feel you get with too low of pressure, since the sidewalls will flex laterally more.

Now with rims that are as wide as the tire or slightly wider, then the outside sidewalls are pre-stretched into the cornering state. Then when you turn the wheel, the tread and sidewalls only have to flex 1" or less before it stabilizes and pulls on the rim.

Here's a guy that put 335mm rear tire on his 951...
http://pages.prodigy.net/pjbloom1

And I'm now looking at the Lindsey's RR10 wheel:
http://www.lindseyracing.com/wheels.htm
Looks like they would weigh in at about 15&16lbs for 17x10/11". That's about as light as forged Fuchs in 16x7/8".

Doc, when's your next track event?

DanD

Doc, Dan and others running big wheels with big tires.

Can you post the details about the setup?

What offset, backspacing, width, tire size?

Doc, do you have part numbers for your recent purchase? Or were they 3/2 piece wheels that were put together to make the package?

Thanks
DanD
86 951 *2 http://members.rennlist.org/dan10101

Doc

Danno, My next track event is the weekend of the 15th, POC at Button Willow I believe, I have to double check.

I think you'll be happy with the Lindsey wheels, I've heard good things about them and they are just about the lightest I've seen.

DanD, I have to apologise, I don't recall the exact offset, etc. It's been almost a year now. I just told the guy what kind of car I had and he pretty much already had the info. They are hand built 3 piece rims for the record so no need for spacers. In fact I was very specific about not wanting to have to use spacers. For intense track use, I've heard they are not the best idea.

As I mentioned in my earlier posts, I run Kumho Victoracer 255/40/17 tires in the front and 275/40/17 in the rear and (I believe) the front rim is a 10" and the rear is an 11.5" I did have to roll the left rear fender ever so slightly since that corner of the car had been hit at some point before I owned the car, however the right side fits just fine with no rubbing and no need to roll the fender.

Hope that helps.

DanD

Doc,
Sounds like a perfect fit. Thanks for the info.
Do you have any pictures?

DanD

Danno

DanD,

I think 3-piece wheels are your only options in the larger sizes. Although there some Porsche wheels in 18x10" (expensive), but you'd have to install longer studs and spacers to use them.

Here's a photo to Doc's wheels:
http://boards.rennlist.com/upload/lance_waiting.jpg

For maximum cornering power and intimidation, you can easily use the following setup on an '86 944/951 (requires 2.5" front coilovers):

front: 17x10" 35mm offset, 255/40-17 tire
rear: 17x11" 25mm offset, 275/40-17 tire

According to TurboTim, you can actually squeeze a 315/35-17 tire in the back with this combo....wow... I'm going to try the 275mm first and measure the clearances.

Claus Groth

[QUOTE]Originally posted by TurboTim:
[QB]With the correct offset and alignment, along with rolled fenders, you can fit a 315 in the back.

Tim,

I'm going to purchast track wheels soon and would like to consider 315/40-17 tires. Please elaborate about offset and fitment.

Thanks,
Claus Groth

instigator

i have a couple of more questins. i see that the 235/45 & 265/40/17s are about the same dia. as the stock tires that came on the car 215/60/15 is there a reason that these tire cannot be used instead of the 225/45 & 255/40? i just want as wide as a tire that can be used without rubbing. and the second question. what is the recomended tire pressure for this size tire? thanks

TurboTim

I have seen a couple cars with 315's on the back.All of these cars had stock fenders.Unfortunately I dont know the width of the rims and the offsets.

Tim
86 951 http://www.speedforceracing.com

instigator

the rims are the 993 aftermarket from milli miglia 7.5 fr 9 r

schless

Decided to buy used set of 4 Phone Dials of from P.A.B. in Gorgia, comes with 3 fairly new tires.

Incedentally just took 2700 mile trip
to Detroit and back on the nearly balt
Goodyear and the BENT spare wheel.


will a 245 scrape wheel well opening?

also I need a rear whell for a '86 951
p/n 951.362.116.00[/QB][/QUOTE]