jpNcos

Any negative effects on turning radius running 265

dprantl

There's a guy here who runs CCW 18x9 (or 9.5?) ET68 with 265's all around. I don't recall him having any problems, but maybe he will chime in.

EDIT: Here's a post by him with the wheel/tire info: https://rennlist.com/forums/6887262-post8.html

Dan
'91 928GT S/C 475hp/460lb.ft

GlenL

Like Hacker was getting at, it's all about specifics once you push the envelope. Different brands and models of tires have different real widths and profiles even if they've got the same numeric dimensions.

What are you trying to accomplish? What are you willing to put up with? Roll the fender? Double-up on steering rack stops? Rubs with body lean?

Go with 8 or 8.5 unless you're looking for track wheels. Stick to good offsets (~55mm) and moderate tires.

And keep in mind that 17" tire choices are fading away. Check on the number of types available in what you think you'll need before commiting to the rims. I never thought a 222/75/15 would be a rare tire.

F451

I was running 18 x 8 1/2", ET 52, 245/40 ZR18 and it worked fine.

Had a slight rub on very hard bumps in a sharp turn, never worried about it, and never saw any rub marks on the tire.

Rear was 18 x 10", ET 65, 265/35 ZR18

F451

My current setup is:

Front: 18 x 10", ET 65, 265/35 ZR18
Rear: 18 x 10", ET ET40, 265/35 ZR18

No rubbing, but I am getting some tramming and a shimmy which I'm attributing to the wider front wheels/tires accentuating the worn suspension parts in the front (rack, rack mounts, tie rod ends, etc).

James Bailey

Always keep in mind that the stated "width" 225,245,255 is NOT tread width but the widest bulge of the SIDEWALL measured mounted on a rim width determined by the manufacturer....so they vary greatly ! Actual tread width is always less....in the photo above the 275 x 18 has 10 inches of tread the 225x 50 x15 has 9 inches of tread at least it used to Ed Ruiz was always the first to point out that contact patch does NOT increase with wider tread it becomes wider but shorter which does benefit cornering ability somewhat just not nearly as much as most people think !

jpNcos

I like to take the 928 on mountain drives and may at a much later time want to do some light track events. I would rather not roll the fender. I can get a screaming deal on the 8" wheels, but the 9" are not as bad as I was thinking. I would like to enter the car in some local car shows but my OCD does not allow strangers that close to my car. Other car guys is one thing but every time I go to a car show some of the things I see makes me sick.

I don't see this problem with 17" tires and don't really want a 18" wheel "the roads around here would not allow it"

jpNcos

Do you notice any reduction of turning radius with the larger width?

F451

No, but that's not something I would pay attention to necessarily. No problems in normal driving, parking lots, the driveway, etc.

JWise

Subscribing, with a vested interest.

redpathtribe

Josh,

Go for the 9" Cup II's if you can get them, just for the ultra cool, uber rare factor if nothing else!

If I would have known they were out there when I was looking for the 8's, I would have tried like crazy to track them down.

FWIW, in looking at DR's site and an old DEVEK catalog, the 9.5"x17" Cup I's (et68 IIRC, used on some of the 928 Cup racers?) are recommended with 255/40's on the front. I think the cool set up would be to have 4 of the 9" et70's with 255/40's all the way 'round, then you could rotate them too. The 928 is so well balanced, I think having the same width tires all around would work well (talking street and light DE duty here).

The way you're describing how you use your car, I'd go this route since you don't want to roll the front fenders out. You could put up to 275/40's on the 9" rears (lots of guys doing it), but I think you may have some rubbing issues up front with anything larger than 255/40's... unless you roll the fender...

redpathtribe

Jarrod, you found some!?! Awesome!

JWise

Yes, and I have another little surprise on the way.

Thanks!

redpathtribe

You are THE MAN

Ispeed

9.5x18 et68 with 265/35/18 fronts. No rubbing, but the steering is a little heavier than with the original flat wheels.
I did have 8x17 et70 fronts with 245/40/17 and had to run a 5mm spacer to not have rubbing on the inside. I now have the smaller diameter hypercoil springs and they probably wouldn't rub.