I'm buying 18" carrera III wheels. Many 928 owners run these wheels.

Fronts are 8 inch with offset of 57
Rears are 10 inch with off set of 58

From what I understand they fit the 928 like a glove.

Will I need spacers.
Will I be able to fit 295's in the back?

Thanks

No.

No.

Go 235 in front and 265 in rear and your life will be blessed. People run wider but that xtra 10 isn't really worth the headaches.

295's are tight mine rubbed on the inner fender on hard corners. Personally putting that much tire in the back has no advantages and will increase tram lining. Unless you can get a 245 up front to better balance the difference in tread width.

I would go no more than a 275 out back and at least a 235 up front.

It depends on the tire.

I'm thinking Michelin ps2. The reason I want 295 is the car will get a sc in the spring and will need the additional with to help with traction.

A 285 section should work OK- it did on my late S4 with a ET60 on the rear. Edit- without spacers that is. My memory tells me a quality make 295 would probably fit but it is over 10 years since I lost my late S4.

Your proposed front wheel is better than some but still a couple of bananas short of a picnic at ET57 given you need ET65 to maintain the design NSR. Many seem to put little importance to this but then many do not push the envelope.

Rgds

Fred

Madturk, what year shark are you referring to?.
Just wondering for reference. Thanks.

On my Spyder, I run

Front - 18x8 - offset 57 with Nitto Invo 235/40-18
Rear - 18x10 - offset 65 with Nitto Invo 295/35-18 and 15mm spacer

but my rear fenders aren't stock because of the convertible conversion so I would ignore those for your fitment. If you want to go as wide as a 235 in the front, I would also recommend rolling the front fender lips for extra peace of mind that you won't have contact up there.

http://www.willtheyfit.com/

This is a very useful fitment calculator for both wheels & tires. You can plug in what you're currently running (or what you know others are running) and then what you're looking to go to and it will tell you how the setup differs inside and outside. It obviously doesn't take into account camber settings, brand and model of tire design (some have a more rolled transition from the sidewall to the tread) or things like that, but if you know how much clearance you currently have inside and outside this should get you very close on the max you can go with regard to offset and tire section width.

I run 5 spoke 997 18" rims that are 18x8 (57 offset) and 18x10 (58 offset) and have 235's on front & 265's on rear both front & rear are Mich PS2, no fender work.

I get zero rub, additionally I don't see how anything wider than the 265s I have fitted would fit in the non modified wheel well.

You wont have THAT much HP.

255s with LSD would be enough, 265 for sure.

Too wide against the fronts and you end up with other issues.

265s on 10s is perfect.

There is no such measurement.

Section width is -the- critical measurement, but it has nothing to do with 285, 265, etc. It is a separate measurement done in inches.

What do you mean - section width is the tire width spec and what the 285 woudl be from FredR's post. See graphic from Tire Rack below.

He will if he calls Tim Murphy....

Here is Tim himself in his automatic S4 Stage 3.

If my memory is correct, those are 295's on 11" wheels out back.

Section width is an actual value, 285 is not related to that number at all.

A tire can be more square than another, and they can be closer, or by that image, NOT square at all, and way different.

In other words, every 285/40 tire out there, will have a different section width.

The "tread" width means nothing.

No! 285 is the section width. It's the definition of "section width."

What they never say is how wide is it at that point that'll be closest to the fender or shock or whatever bit will be closest. That's usually some point between the biggest bulge and the tread getting near the inner lip of the fender.

Now, unless the cars are the same weight, rims are exactly the same width and diameter, tires are exactly the same, fenders are the same, etc., etc., etc., there's big risk trying to match what someone else made work at the edge of fitting.

What you don't want to do is get big tires and find that they don't work. I got some 245s and 275 off CL and mounted them up. The fronts only work because I've got S4 arms on my early cars and, oddly sometimes the rears touch the fenders for a second. Another model of tire in that size might work fine. Another model in those sizes might not work at all. Then there's the track tires lthat seem to work but the 245 Hoosiers I mounted up that touch the lower-back section of fender in tight turns.