the **UNOFFICIAL** Jeff Alton fuch my 930 thread

[les_garten]

Originally Posted by sand_man

Even though my degree is in accounting, boy I wish I would have paid attention to those Catholic Nuns trying to teach me math and science, back in the day!!! I feel like a dumb blonde (even though I have black graying hair) when it comes to gear ratios and such!!!

I'm not sure I believe this story, let me see the back of those hands?

[sand_man]

Originally Posted by les_garten

I'm not sure I believe this story, let me see the back of those hands?

Man, no doubt Les...those freaking penguins will leave a mark on yo azz!

[les_garten]

Originally Posted by sand_man

Man, no doubt Les...those freaking penguins will leave a mark on yo azz!

Hmmm, OK, Sounds like your story is validated... Sorry for doubting you.

[RarlyL8]

I try to stay near the stock tire height nomatter what the wheel diameter. Going too tall begins to look cartoonish.
For example:
245/55-15 = 25.6" tall
245/50-16 = 25.6" tall
245/45-17 = 25.7" tall
245/40-18 = 25.7" tall

Doesn't accounting involve a little math?

[DDDD]

Okay, but most of us start out at 245/45/16, which from memory is like 24.86".

So any of us going from that size are moving up almost an inch in diameter by going to the 17"s. This is the same as having slightly taller gears.

My friend with a normal aspirated 911 went back to 16"s on his ride because he can feel the bigger tires take longer to get rolling.

[RarlyL8]

It is an example.
While being dependent upon tire size availability, wheel diameter has limited impact on tire height. Within the confines of rim diameter, such as 15 to 18 inches, aspect ratio is much more a factor.
For example, if your buddy went from a 245/45-16 to a 245/40-17 the tire height would remain the same ~24.7" with a 1/2" reduction in sidewall height which would reduce sidewall roll for better handling.
I do understand your point though as tire sizes and aspect ratios are limited. That is one problem with running 17" wheels; there are no rear tires manufactured that are perfect height. A perfect 17" rear tire (to me) would be 335/30-17. Front = 255/40-17. They don't exist.

[NathanUK]

It wouldn't hurt my 930 to have slightly higher gearing as it has a G50/01 and I think 5th gear may be a custom ratio as it's not that different to 4th. My car in theory will only be able to do 160mph due to the gearing according to the rev counter and the speedo. IIRC I do about 75mph verified at 3000rpm

[PcarPhil]

Originally Posted by Jeff Alton

There are 9's and 11's in the first production run.

Currently the build data looks like this....

7.5 and 8.0 for SC/Carrera front
9.0 for SC/Carrera rear

9.0 for Early turbo front
9.0 for Late turbo front
9.0 for turbo body with SC/Carrera chassis front
11.0 for turbo rear
11.0 for turbo body with SC/Carrera chassis rear
11.5 for turbo rear


cheers

Jeff,

Im curious - does the 9.0 for SC/Carrera rear have the same specs as the 9.0 for Early turbo front or the 9.0 for turbo body with SC/Carrera chassis front?

I've got a set of 9x17 front Fuchs weldups based on 9x16 Fuchs backspacing and offset measurements and they fit perfectly. These are on my '77 with widebody panels.

[PcarPhil]

Originally Posted by DDDD

Okay, but most of us start out at 245/45/16, which from memory is like 24.86".

So any of us going from that size are moving up almost an inch in diameter by going to the 17"s. This is the same as having slightly taller gears.

My friend with a normal aspirated 911 went back to 16"s on his ride because he can feel the bigger tires take longer to get rolling.

If you're referring to me I actually picked up a set of 15" Fuchs with 24" tall tires - mainly for the less unsprung weight and gearing differences.

My 15" setup on my NA car doesn't apply too much in this 930 thread. Also a quick fyi - my rear 275/40/17 Azenis measure out to be 25" tall on the 11" wide wheels.

[DDDD]

Originally Posted by Kaefer

If you're referring to me I actually picked up a set of 15" Fuchs with 24" tall tires - mainly for the less unsprung weight and gearing differences.

My 15" setup on my NA car doesn't apply too much in this 930 thread. Also a quick fyi - my rear 275/40/17 Azenis measure out to be 25" tall on the 11" wide wheels.

That's pretty unusual for a 275 to be only 25" tall. The tire must be lower profile than others in the same size range, no?

Did you keep the 17s?

[RarlyL8]

The 275 is only 25" tall because it is stretched on an 11" rim. Remember an 11" rim is actually 12" wide. That means the 10.8" wide 275 is using part of the sidewall to span the gap thus reducing sidewall height by 1/2" inch or so.

[PcarPhil]

Originally Posted by RarlyL8

The 275 is only 25" tall because it is stretched on an 11" rim.

Yep. The max rim width for a 275/40-17 tire is an 11" wheel. As a wheel gets wider for a given tire size the overall tire diameter gets shorter.

[rooked 930]

Thanks for all the info on tire widths vs. rim widths.

I'm set on going with 11's on the rear.

Now, who makes 315's in 17" these days? And for how much longer...?

I think 18" will detract from the somewhat classic / sleeper look I'm trying to keep (one reason why I won't go the Kinesis route, even though I really like their wheels)... although the Zork may have already done that.

rob

[Jeff Alton]

Are you looking for R comps or high performance summer tires?

Cheers

[WPOZZZ]

Originally Posted by rooked 930

Now, who makes 315's in 17" these days? And for how much longer...?

Sumitomo HTRZ
Dunlop SP8000
Goodyear F1 GSD3

[930gt-40r]

Originally Posted by rooked 930

.
Now, who makes 315's in 17" these days? And for how much longer...?

I also think (could be wrong)that this size is still widely used among the late model Trans-Am and Camaro Z-28 guys.
Sorry to butt in.

[Jeff Alton]

Here is a 17x9.0......

This wheel will have a couple of changes to it.

The wheel outer wheel shell will be changed to look more like a fuch with a ramped profile and a soft lip.

The wheel can be either blind mounted, like in the pics, or through bolted.

The gap between the center and the rim shell will not be there on the production parts.

This one will go off to get load tested.....















Cheers

[WPOZZZ]

::sniff, sniff:: ::wipes tears from eye:: Those are just beautiful!

[930gt-40r]

Its beautiful Clark!

Those are really nice.

[Reaper930]

Stunning, can't wait to see them mounted up with some rubber. Absolutly beautiful.