mpiffaretti

I have a 911 SC body, with a recent 3.6 964 conversion, which produces way too much torque for my 15 x 7 and 8 inch Fuchs.
I have recently found a set of decently priced BBS RS 16 inch with the intent of increasing diamater and have more tire options.
The set has the following specs:

9x16 ET 11 REARS
8X16 ET 28 FRONTS

Per my research seems that the fronts would fit by adding a 12 mm spacer (to bring offset to +15), but I'm not sure about the rears.. I do have some camber, and the fenders are rolled, but I still dont know if they would fit or not.
Can anybody chime in if the above offsets would fit and what tire sizes?

Bill Verburg

Spacers can only lower the ET never raise it.
8X16 ET 28 FRONTS is a good fit in front the recommended range for an 8 is ET25 to 30, tire would be a 225/50 or 225/45
9x16 ET11 is a bit aggressive in back and close to the edge but a 245/45 ought to work

a much more efficient way to go is
BFG G-force Rival S 1.5
8x15ET27 225/45
9.5x15 ET19 245/40

You'd have to have some custom o/s 15s made

mpiffaretti

Thanks Steve, I was hoping you would chime in!
would love to keep 15’s but tire options are limited plus im trying to increase diameter while retaining period correct looks... a lot of conpromises

Bill Verburg

Steve????

Any time you increase the diameter of the tire or the weight of the assembly it will sap performance, In the extreme 5--60 lb-ft. Diameter increase is the worst in this regard, additionally diameter has a major effect on fitment. Of course there is aplay between diameter, width and offset.

as a for instance the BBS wheels 9ET11 may be doable w/ a 245/45x16 but less so w/ a slightly taller 225/50x16 and impossible w/ a 255/50x16 all because of tire height

A 255/40x17 on a 9ET15 or 9.5ET19 would fit fine, because of the wheel Et and lower tire diameter.

mpiffaretti

Thanks BIll!!! sorry buddy didnt meant to call you steve! LOL.
And yes, I am aware that a larger diameter will sap performance, but with 310 WHP on a such a light car (on 15 fuchs with a 40 profiled tire) my first gear just cooks the rear tires at WOT.
I appreciate your feedback on tire sizes, you have no idea how much hassle and headaches you just saved me!

Martin

Bill Verburg

I understand your thinking, I went through a similar process when I did my first 3.6 t/p. The main reason to go to a taller tire is to get more reasonable cruise rpms. But it's still a balancing act, you don't wan to go too far. I went from 7 & 8x15 to 7 & 9x16 to 8 & 9.5 x17, rears were 225/50 to 245/45 to 275/40 to 255/40.

I'd highly recommend 17 just because of tire choices, w/ 8 & 9 215/45 & 245/40 or 225/45 & 255/40 is a pretty good compromise

racerbvd

I have a set of 8&9X16 BBS rims that I use on my 88 Carrera . Just had to roll the front fender lips

sithot

Here are 8" & 9" Ruf Speedline wheels. Ruf recommends 215/235. These wheels are running 225/265 which fit but it's close. If used they'll probably get 225/245. Tire choices dictate this.

sithot

"Rear" 265/17 x 9" and a 225/16 x 8" The Ruf 8's and 9's work great on SC's and Carreras.

Bill Verburg

The early Ruf Speedlines pictured are 8 ET30.4 & 9 ET17.7,(both have ETs that are on the side of caution placing the wheel/tire assembly a few mm more inboard than usual) tires would be 225/45 & 255/40 or 215/45 & 245/40 x17 for most usual driving situations

Here you can see the fitment boxes for an SC/Carrera, In the box works, the closer to the edge the more potential issues will need to be adressed

sithot

Thanks for the chart, Bill. Sort of like the 7R wheels which were backspaced to fit the body. The Ruf wheel was on a 930 and the 265 was no issue. On an SC it's a little close for comfort; I have not run them much and went back to my stock 7 and 8 Fuchs setup with what may have been the "last" sets of RE11 Bridgestones.. When I decide on tires I'll make the switch.

Best,

Tom

racerbvd

I have a set on my 81 SC that I am building.