si Banker

At this time my 1987 911 coupe has 6 inch fronts and 7 inch rears. I am moving the 7s up front and am purchasing either 8 inch or 9 inch wheels for the rear. I will use the car as a daily driver and autocross.

My questions are:

I want to run 245s in the rear. Are the 9 inch wheels necessary?

By moving the 7 inch wheels to the front could I run 225s on the front with out getting in to doing any mods to the wheel wells?

The car has been lowered to euro height.

Any suggestions on tires would be appreciated

Bill Gregory

On the rears, you can run 245's on 8" rims - PCA club racers in G Stock can run 1" over stock, and run that combination. 245's mounted on 9" rims is a better combination, as it moves the sidewalls out, which stiffens them up a bit.

JackOlsen

You'll probably want to run 245's with 8's or 9's. Nines are more expensive, and are not necessary to run 245's. There are some advantages to nines over eights, but it's a pretty subtle difference.

225's will fit on some cars, but not on others. You generally have to roll the fender lip and run fairly aggressive negative camber (for a street car).

245/205 is not an uncommon combination.

JackOlsen

Whoops. Bill beat me to it.

85 3.2 Carrera

...the debate goes on! without getting into too many nuances, such as tire dimensions, contact patch, and Fuchs' lip design, I recommend sticking to the stock Turbo setup:

front - 205/55 on 7 by 16 Fuchs
rears - 245/45 on 9 by 16 Fuchs (splurge on the 9's, they're worth it)

That's what I run on my narrow-body '85 Carrera which is lowered below Euro spec height (but above race), and it handles like a charm.

As for tire size/wheel width, if you stick to 8 inch rears, I would go with a smaller tire (225) that runs a wide contact patch rather than a larger tire (245) with a similar contact patch! Tirerack has those specs. You would be amazed at the variance in tire dimensions from manufacturer to manufacturer, even with the same tire size! I feel that the excess slop of a 245 on an 8 inch wheel will detract from the benefit of the slightly increased tread patch. I much prefer a stiffer sidewall, as that will theoretically translate to better feedback and crisper turns.

...my two cents!

Dane

Actually while the 7 and 9 Fuchs will work with 205/ 225 front and the 245 rear combo but neither is actaully the correct offset for your car. I have had that same set up on my car. It works but it can be done better with a similar amount of cash outlay.

The 225-45 / 245-45 is a great performance combo on the right wheel for our cars. Problem is factory Fuchs are not the "right" wheel. There are several options available in custom wheels made from Fuchs, along the same lines as what Jack has done for wheels on his car, but these are specific for our car's flairs and offsets.

Bill Gregory

Without a commercial plug, can you elaborate why the 7" and 9" Fuchs are the wrong offset for an 87 911?

Dane

Neither wheel was made for SC flairs as we now use them. They were made for other applications and we adapted them to the our own uses and our cars.

There is a lot of room unused in front wheel wells with 7 and some in the rear with 9s which is why the BBS and Fiske offsets allow 235 and 255s easily on an SC.

Same reason why Bill Verberg, Jack and I all have custom offsets (none of them close to the original Fuchs #s) on our own cars.

The 7" Fuchs and the 8" 944 turbo wheels will work up front but not as well as they could and they need more clearence for bigger brakes, like a set of 930s. Porshe didn't intended us to be using a wheel designed for a turbo flair, wider track and offset on the earlier cars. They were never designed for that use. Work? Sure but not as well as they might.

If more is better then the 225/245 combo or 225/255 combo is better on a Carrera or SC IMO as long as you don't rub. No way I would recommend 245s on a 8" rim as a performance setup when 9" or better is available.

Bill Verburg

The +23.3mm 7s are a perfect fit in the front w/ 205/55 or 205/50x16 tires. My car came stock w/ that o/s in the front. 225/50 will require lip work and usually extra camber to work especilly on the +23.3mm 8s which really should have more o/s but can be made to work on the front of a Carrera. Several people have had good success w/ 225/45 on the 8s in the front. When additional o/s is used the interference shifts to the inner fender panels where it isn't much of an issue.

IMHO the +15mm 9x16 Fuchs is a better(perfect) fit w/ 245/45 than the +10.6 8s. The 9s are worth every additional penny for the performance oriented owner. The posers can stick w/ the 8s.

I have different o/s for 2 reasons,17s and 9.5" rear.

Bill Gregory

I ran 930 brakes on my SC with 8" 944 Turbo wheels and 225's in front just fine. This is a combination that has worked for years, with the caveat, as Bill V pointed out, that more negative camber and/or fender lip rolling/cutting is required.

Although one can always go to Fikse/HRE/Kinesis type of 3 piece custom wheels, there are many who like a Fuchs solution, and fortunately there are several choices in the 7"- 9" range - all of which have been well documented.

Dane

Sure it works..I have used the 944s myself. I also have 930 brakes and 8 wheels. Are the 944s or 7" Fuchs a good fit with 225s? No, which is why you have to monkey with cutting the caliber fins off, rolling fenders and camber. It can be done better.

The better answer is to have the correct width wheel with the correct offset.

While the original Fuchs work there are better options today, with the same cosmetics and strength, which is why I mentioned it.

I have different offsets because the factory 7 and 9s were never made for SC flairs or cars. Easy enough to get 8s and 9.5 that are correct and take advantage of the car's potenial with 16" tires.

The most you can stuff under the front of an SC body work with little or no trouble is a 9.5" to 9.7" section width on the tire. The rear will take a 10.5" to 10.8". A 225/245 SO3 combo (which drives very well on street, DE and light track use) will give you 8.4/9.1 for a tire patch. 235/265 8.7/9.7...closer to the 9.5/10.5 max. Other tires will offer more and less so you need to shop carefully. I want the most I can stuff under my car on 16" rims with no additional issues. Custom 8 and 9.5s are the answer to that quest.

Unless you have over 250/260 HP the 17" tires and rims weight too much IMO for a performance car.

JackOlsen

With wheels as light as ours, isn't a comparable-overall-diameter 16-inch set-up going to weigh more than a 17? If memory serves, my tires weigh twice as much as my wheels. Shorter sidewalls means less rubber weight, and more aluminum, which is lighter.

Am I wrong about this?

Dane

Tires weigh more in 17" than the 16" in comparable widths. The wheels were a wash when I compared my 11x9 Fuchs and 17x9 Fiskes with the nod going to the Fiske's but just barely.

More importantly for the smaller engines IMO is the gearing change from 16" to 17" which I had forgotten to mention.

Everyone talks about short gearing and the easiest way to get it is stay with the smaller tires.

JackOlsen

Well, I did some quick research that points in the other direction. It's not easy to find actual tire weights on the internet -- but I found, for Dunlop SP-9000's that the following was (probably) true:

Size-------------Weight in pounds

245/40-17---------23.9
245/45-16---------25.1

Then, for wheels, the comparison might not be fair (or accurate, since it's not the same scale). But Sherwood Lee has accurately measured 16x9 Fuchs at 20.0 pounds. My 17x9 Lindsey 2-piece Fuchs weighed 17.5 pounds when I weighed them (although this was using the bathroom scale method, which isn't super accurate). Still, even with a 10% accuracy margin, the Lindsey's are lighter.

Total weight for the 16-inch setup is 45.1 pounds.

Total weight for the 17-inch setup is 41.4 pounds.

That's a pretty significant difference. And the outside diameter of both tires is effectively identical. The Miatanet calculator puts them both at 24.7 inches, although there's a one revolution difference per mile, so it's not exact. The gearing would be identical between the two, but the 17-inch set-up would be almost 4 pounds lighter.



Now, I also found another tire weight (Bridgestone RE-71's, I think) that listed a 1-pound heavier weight for the 245/40x17 than the 245/45x16. This doesn't seem to make sense, though, since they're both the same size tire (same outside diameter, same width), with the sidewall on the 17-inch one being 1/2 inch smaller to accomodate the larger rim.

kahuna

I love this, some idiot who by his own admission bought his first 911 a year ago is telling us that the wheels and tires many of have used for years don't fit right.

FYI, I have 205/55 and 245/45 on Fuchs 7 and 9 they fit perfectly and yes, w/ big brakes.