FIRE!

 

^lol.
It's crazy to think we won't get an 18" fitment with tire. Dammit!

 

A quick correction, our pricing starts around $3500, rather than $5K, for our 991 GT3 19 and 20 fitments.

 

Do we have an idea of what the stock wheels weigh?

 

Bump for stock wheel weights

 

Serge - why a new 991 GT3 wheel thread if you didn't care from deviating from stock? just confused from other thread since you were bashing on going lower to 19". Change of heart?

Great OFFICIAL thread though for wheels and tires

 

Front 24 lbs
Rear 26 lbs

 

Finally. Thank you sir.

 

Hello,
Can anybody help me to measure 19" rear wheels that fit PCCB (991 turbo 390x32 rotor)
I was offered a set of forged rear wheels (used) with inner DIA is 444mm , i'm not sure if it enough to fit PCCB
Who ordered HRE or Forgeline, can you help me with this information

 

We get a ton of wheel fitment questions from car owners and wheel manufacturers, so I'll throw some tips out there for those of you browsing track wheels. Brake clearance is something to always keep in mind when shopping track wheels. There's not much worse than buying a $6,000 set of wheels only to find out they won't clear your intended brake package!

Wheel barrel clearance and wheel spoke clearance both come into play when choosing wheels. Barrel clearance is much more of an issue with PCCB discs (410mm diameter) than it is with the OEM iron discs (380mm diameter). On the GT3, that issue is compounded because the OEM caliper is incredibly tall with a fixed bridge on top. Spoke-to-caliper clearance depends on the spoke design and curvature, NOT just wheel offset (which is what people many times assume). You can have two wheels with the exact same offset that offer drastically different caliper clearance due to the shape and curvature of the spoke. Please don't fall into the trap of assuming that just because two wheels are a +52 offset, they're both going to automatically give you the same wheel spoke clearance...they're not!

Another rule of them is that you want at least 2mm of clearance between your brake calipers and the wheel in all directions. All of your wheel and suspension components see incredible loads on the track, and they can deflect and deform a bit. Having 2mm of clearance will help ensure that brake components aren't making contact with the wheels, which can cause serious issues as one can imagine.

Something that people frequently forget about are wheel weights. When installing your wheels, you need to make sure your stick-on wheel weights inside the wheel barrel aren't going to make contact with the brake caliper. You do so by A) checking the weight location and B) slowly rotating the wheel while the car is still in the air. I'd also recommend taping the wheel weights down so they don't come loose, flop around, and destroy your brake calipers.

Below are the wheel fitment templates for our front and rear Essex Designed AP Racing Radi-CAL Competition Brake Kits. Our system shaves 33 lbs. of unsprung weight vs. the OEM iron brakes and offers superior wheel clearance, even though the disc in our system is larger in diameter (AP Racing=394mm vs. OEM iron=380mm). That is possible because the AP caliper isn't nearly as tall as OEM, and the AP Radi-CAL has internal fluid pathways (no bleed screw or crossover tube hanging off the end of the caliper). Numerous customers of ours are running our kit inside 19" wheels. Our front system actually sits completely inside the envelope of the OEM iron system. As a rule of thumb, if the wheel in question clears the OEM iron brake system safely, it will clear our Essex/AP Racing brake system as well. Our setup provides ever-so-slightly more room.

Front Essex/AP Radi-CAL wheel fitment template

Rear Essex/AP Radi-CAL wheel fitment template

The front kit is where things are going to be close. While we still advise checking the rear, there is usually miles of clearance and it's not an issue.

Below is a pic that shows how to use our fitment templates. When you print the template, always check one of the printed dimensions with a ruler before inserting the template in a wheel. Printers like to do wonky scaling, and you may find that the document did not print with the proper dimensions.

Finally, if you're unsure if a wheel will clear our brake kit, email the fitment templates above to the wheel manufacturer. We frequently talk with the guys at Forgeline, Finspeed, Signature Wheels, etc. In many cases, members of their team run our brake kits on their own cars, so they're familiar with our fitments and what we're doing. They can check clearance and help you avoid a costly mistake.

Hopefully this post saves some folks from making an expensive oopsie. Thanks and happy wheel shopping!

Edit...one final note: If you do happen to check brake clearance on a particular wheel, please make note of the brand, model, and offset (i.e. Forgeline GA1R 19x9 +52). Pics are always welcome too. That will add value to this thread and save your fellow owners, the wheel folks, and us lots of time and energy! Thanks again.

 

All good information from Jeff. I would add that 2mm really isn't enough. I believe that's what Brembo specs for caliper clearances, and with that gap plenty of debris got wedged between the caliper and wheel barrel on my setup, to the point of damaging my front wheels (non-Porsche). To have a better chance of avoiding damage go bigger than that.

 

Who have template of stock rear PCCB yellow brakes/calipers? )

 

Good to see you on Rennlist! We had a chat yesterday about this. Again to confirm 19" R101's on the rear of your 991 Turbo will work, but it would have to be 20" up front due to the PCCB's.

AIM Performance at the time broke the VTG Turbo world record. 0-60 in 2.2 seconds and 60-130 in 5.3 seconds. This thing is an absolute beast using 19" R101's on the rear:

 

This track duty 6 pot RB caliper (RB6M2) is engineered for a direct replacement to OE red calipers with a bolt on installation (no spacer or adaptor), and can fit under most 18" wheels - Just shipped one order last week.

Similar 6/4 pot RB calipers kits for 18" wheels are offered to BMW M3/M4 (E90/F80), Viper ACRE, Nissan GTR, and Mustang GT350.

• Much more choice and save money on 18" wheels and tires.
• Standard FMSI# pads: Same as Corvette ZR1/Camaro Z28 (D1395), Mustang GT500 (D1666), GTR means familiar brake pads choice at lower cost.
• 100% swappable between iron and carbon rotors

RB brake system makes a lot of sense to those serious track people who wants the best value and retain their freedom of choice on other consumable components.

Same kit installed on David Donohue's 991 Turbo