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Discussion Starter · #1 ·
Does anybody know how similar the 718 rear suspension is to the 981? The reason I ask is I'd like to run 19x10.5 rear wheels on my 718 CS at SCCA legal offset and I'm concerned that the wheel might hit the ball joint on the track rod. I've read several posts from 981 owners that have fit 19x11's on their cars so my assumption is if the geometry is similar or even better it's the same then I should be able to fit them on the 718.

I did find a few photos of the GT4 rear suspension and, other than the threaded body struts, it looked to be almost identical. I've read you can fit a 19x11 on that rear and as well.
 

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You can order the 718 CS with either 20" 911 Turbo Wheels for $3,570 or 20" Carrera Sport Wheels for $2,560. Since these are standard options, they fit the SCCA definition of "standard".

Both options are:
8.5 x 20 ET 57 with 235/35 ZR 20 tires (front)
10.5 x 20 ET 47 with 265/35 ZR 20 tires (rear)

The fact that they offer the car with 10.5" rear wheels from the factory makes it logical that 10.5" wheels should fit. SCCA will allow you to go down one inch, so 19" should be fine. The two things I see to be careful about is that the $0 wheels have a rear offset of 45, whereas the 10.5" have an offset of 47. Since SCCA allows 7mm you would max out the rules with a 40mm offset on the 10.5" inch rims. You also can't mix and match options, so you would have to run 8.5" front with your 10.5" rears.

The rules get a bit complicated, so my feelings won't be hurt if someone points out I missed something.
 

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Discussion Starter · #4 ·
You're correct that the 10.5 & 8.5 widths are factory in 20" diameters . My concern is looking at my stock 20x10 rear wheels, the inner lip of the wheel is fairly close to the track rod ball joint. If I narrow the wheel radius by 0.5" I'm thinking the rim might hit the ball joint. I've considered that moving the offset from 47mm to 40mm should move the additional 1/2" of wheel width all to the outside. But because I have to have 19x10.5's built, I'd like to know if anyone has successfully fit a 10.5 or 11 width in 19" diameter to a 718 yet?

Looking on line at photos and illustrations of the GT4 rear suspension, it looks to be similar... and although they run 20x11's I'm not sure what offset or if they also have clearance issues with that ball joint when running a smaller diameter?

Last thing, your interpretation of the scca rules is correct... you can not mix and match options. If I run a 10.5 width at the rear I must also run the 8.5" width up front, which is exactly what I intend to do.
 

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Any updates on any other running 19x11?
 

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see this thread.
 

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Does anybody know how similar the 718 rear suspension is to the 981? The reason I ask is I'd like to run 19x10.5 rear wheels on my 718 CS at SCCA legal offset and I'm concerned that the wheel might hit the ball joint on the track rod. I've read several posts from 981 owners that have fit 19x11's on their cars so my assumption is if the geometry is similar or even better it's the same then I should be able to fit them on the 718.

I did find a few photos of the GT4 rear suspension and, other than the threaded body struts, it looked to be almost identical. I've read you can fit a 19x11 on that rear and as well.
I've read this in so many reviews...now off the top of my head I want to say the 718 rear suspension derives from the 981 GT4.
According to the Tech document on 718


As part of the continuous process of adapting the chassis of the Porsche 718 Boxster
models to the increased customer wishes and sporting challenges, the following
optimizations were implemented:
• The wheel width on the rear axle was increased by 0.5 inches compared with the
previous model (with unchanged tire size)
• The springs, dampers and anti-roll bars were also retuned to adapt them to the
new chassis

• The speed-sensitive power steering is an enhancement from the Porsche 911
Turbo model year 2014 and is functionally extended with lane change assist
• The new sports steering wheel with the optional Sport Chrono package includes a
Mode switch for selecting the different driving modes directly on the steering
wheel
• The size of the brakes has been increased in line with the enhanced driving
performance
• The PCCB of the 911 Carrera model year 2012 is optionally available for all models
• All models are equipped as standard with the third generation of the Tire Pressure
Monitoring system
• The software of the chassis control systems was adapted to the increased power
of the new turbo engines
• All models can be optionally equipped with the cruise control system with braking
intervention function
• The engine and transmission mounts were redesigned and are integrated in the
Rear axle 4_02_17





Front axle 4_01_17
The wheel carriers, wheel hubs, wheel bearings and control arms were adopted from
the 911 Carrera MY12 for the 718 Boxster MY17. In addition, the springs, dampers
and anti-roll bars were retuned. The increased anti-dive characteristic reduces diving
at the front of the vehicle during full braking and shortens the braking distance.


Rear axle
The Porsche-optimized MacPherson suspension used on the 718 Boxster models is essentially
the same as the suspension used on the previous model. The springs, dampers and anti-roll
bars were also retuned here.
proven PADM system

4.1
 
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