Returning to Porsche Fuchs Wheels
Finally got the rolling stock this car deserves.
Funny how one can know the validity of a concept but not realize its magnitude until you actually experience the results first-hand. Every car person knows that lighter is better. Most car people know that less rotational inertia is better but I don’t know how many of them are aware of HOW much better it can be.
Before every car came with factory 20” wheels it seemed like one of the first things people wanted to do was fill the wheel gap with more wheel and tire, mostly for aesthetics. This is almost mandatory in the off-road community. Bigger tires equals more capability whether you are flying through the desert, crawling over rocks, or floating over mud. However, if you don’t require larger diameter wheels and tires, stepping down in diameter and weight will not only shave overall weight off the car, but will reduce the amount of torque required to get the tires rolling and stopping. So the smaller rotational inertia will allow your wheels and tires to spin up faster, like a spinning figure skater pulling their arms in.
If you recall several years back, when I bought my car it came with 17×7.5 and 17×8.5 ROH ZR6 cast wheels. These are taller and wider than stock. They were never my favorites but they were low on the priority list of things to fix since they were literally one of the few things not broken on the car. I knew I wanted to step it back down to 16s at some point but that fell on the back burner while I rebuilt the rest of the car. 6.5 years later, I still had the 17s.
Fast forward to 2021 and I bought an old Tacoma with huge 285 70 17 tires on it. It looked rad but they were too big as they rubbed near full steering lock, and off-the-line acceleration and braking were not so great. On rough roads it rode like garbage. Yes there are ways of overcoming all those problems but this was a daily driver pickup truck for Home Depot runs, not winning the Baja 1000, King of the Hammers, or King of the Campground.
In the back of my mind I knew if I stepped down a tire size, handling would improve, but mostly I was done with the tire rub. Stepping down from 285s to 265s turned it into a brand new truck. All of a sudden I had torque everywhere. It had more giddy up, better stopping, and the ride was more comfortable. To be honest I kind of want to step it down further to stock size tires again. I bet with the manual transmission it will be a rocket! 🙂
After that a-ha moment, I immediately turned to the 911 and looked at the 17s. Staring straight at me was some cheap performance to be gained.
If you want some data to analyze, here is a static weight comparison of my 17” wheels and tires with 16 and 15 inch fuchs and corresponding tires.
You can immediately see that there is a huge weight reduction in stepping from 17s to 16s. The weight savings from 16s to 15s are less dramatic, but it exists if your target is absolute minimum unsprung weight.
I managed to buy a used pair of 16×7 genuine forged fuchs, and a new pair of 16×8 Maxilite cast replica fuchs. The SC originally came with 15” and 16” diameter wheels with 6s in the front and 7s in the rear, but I am running a well-documented 911 Turbo setup, which has 7s up front and 8s in the rear. 16x9s are also easy to stuff in the rear and 16x8s can be shoved up front but that’s a more involved process for a future conversation.
Real genuine forged 16×8 and 16×9 fuchs prices have skyrocketed along with the cars themselves, so I bought a pair of replica rears just to get the car rolling on the new 16” setup. Ill keep an eye out for a genuine pair of 16x8s or 9s in the future. Fortunately these Maxilite replicas are TÜV approved so they are good quality, are fairly light, and look just like the real thing. I bought them from Mariani Motorsport and highly recommend them. They have a huge selection of wheels and are a pleasure to deal with. I am pairing them with Toyo R1R 200 treadwear tires in a 205 50 16 up front and 225 45 16 in the rear.
My old 17s had Nitto NT01 100 treadwear rubber in a 235 50 17 up front and 255 50 17 out back. I am stepping down both in tire grip and contact patch size, however I am also stepping down in tire diameter, width, rotational mass, and unsprung weight.
On my own car, my bathroom scale says I shaved 11 pounds off each front wheel and 6 pounds off each rear wheel for a total of 34 lbs. Taking 34 lbs off the chassis itself is pretty significant, 34 lbs off rotational mass is a huge improvement worth a few ft-lbs of torque.
So what’s the verdict? Dramatic performance improvement on all levels. The reduction in overall diameter lowered my final drive and that, combined with lower rotational inertia, improved my torque everywhere. Before, the car felt gutless at less than 3000 rpm. Now the useable torque starts much lower and gets very lively after that. The car now pulls harder during acceleration and brakes harder as well. It is so much more exciting to drive at all speeds. After my engine rebuild I assumed these cars were simply highly strung with not much torque down low. This is the way it was always supposed to feel. I enjoy the R1Rs more than the NT01s as they allow the rear end to wiggle a bit more and give me more feedback. The R1Rs are quite capable in the rain too!
I don’t need to tell you that this is the way the car was always supposed to look as well. These are the perfect factory wheels. What a stunner.
I had planned to keep the 17s for autox/track tires but they are better suited for a higher horsepower car that can make use of those bigger contact patches. Ill probably move them along to another home.
And with that I have discovered yet another rabbit hole to fall into. The quest for ever improving lightness…