Mike W

In the process of upgrading my wheels. Planning to go 8.5" front and 11'' rear. . I will be installing PSS9s and thus lowereing the car. Will the 11" width create any rubbing problems? Any downside in going to 11"? thanks

Viken

Given the right offset, you can easily install 11" wheels at the rear. There is no real downside other that a slightly heavier wheel/tire combo. And, if you don't really need the little bit of extra grip from that little bit of extra footprint, you may just want to stick to 10's.

blkblkblk

i have a 97 turbo and i'm considering getting 19X8.5 (+47) and 19X11.5 (+35) wheels from tirerack. eventhough this is a fitment tirerack guarantees, i'm worried that the rears might not fit correctly. from doing some calculations and comparing to the stock 18x10 40 offset rims, the 19X11.5 will stick out 24mm more on the outside and will have 14mm less clearance on the inside.

can you guys let me know what you think about this fitment? if you're running 19x11.5 or 19x11 inch rims, can you let me know what your offset is?

thanks a lot.

Mike W

Viken, My reason for going to 11s is to create a little more "lip" for the wheels. Purely for the bling, bling factor. I am running 285 in the rear but eventually will go to 295. Mike W

msobota

I am in the middle of a big learning experience concerning 11" wheels on my 96 993tt. Mine were ordered 11x18 with a 34mm offset. With this setup and 315-30-18 Michelin Pilot Sport tires (lowered suspension - H&R) I have a bad rubbing problem at the fender lip.

So - New centers for my wheels are being cut as we speak. The new centers will have a 48mm offset. This will move the wheel inboard approx 1/2" and will alleviate the rubbing problem.

It is quite possible that I could have installed 285-30 or 295-30 series tires and had no rubbing but I wanted to run the wider tires.

I now have a set of 3mm spacers and a set of 6 mm spacers to work with once I receive the wheels back with the 48mm offset. This way, I will be able to move the wheel back out approx 1/8 (3mm) or 1/4 (6mm) to achieve the perfect fittment. Installing these spacers will have the following effect. 48 mm offset with 3mm spacer = 45mm offset, 48 mm offset with 6 mm spacer 42mm offset. I am quite sure that this will work for me under many tire configurations for street or track.

If you want the opportunity to run wider tires in the future, you will need to carefully consider the offset you are ordering. I believe stock for a 996tt with the 18" wheel is a 45mm offset and several drivers use that wheel with 285/295 or 315 series tires with good results.

Mike Sobota

Tour18

Thanks for the info Mr. Sobota. I was just about to post the same question as Mike W.

viperbob

I run 996TT wheels, with no rubbing issue at all... My track wheels were 8.5s in front in front with more offset to the outside (for future expansion of another .5" on the inside). I also run my 11" rear tracks with 5mm spacers to the outside. Even with out them, there is no rubbing on the inside. Whether there is another 7-8mm in there, I could not say...

Bob

Mike W

Thanks guys for the information. I do not plan to go bigger than 295 in the rear and I do not want to use spacers. What would be the maximum offset with no rubbing problems on a lowered car, given the fact that I want to have a big a rear "lip" as possible.

msobota

I think 45mm is your best bet since that is a stock 996tt wheel and working well for many other drivers.

Mike Sobota

Mike W

Thanks Mike, Another quick question - I see you have k24s. How much of a difference are they and what other mods did you have to make? thanks

David in LA

Your maximum offset size (and rim size) depends also on what suspension you will be running since coilovers with narrower springs will let you have more tire inboard and hence may allow you to go with a wider rim with a different offset. I would suggest that you lower the car first before buying new rims, or at least doing them at the same time.

Remember that these cars are handmade and there are minute variances from car to car...since others have had no problem with the 11" 996TT wheels these SHOULD also work for you. Once you get away from this size and offset you reduce the margin for error and increase the possibility of rubbing. Also, since you are looking to maximize the size of the lip for the "bling bling" factor keep in mind that the look will also depend on the thickness and also the design (some flat, some are concave) of the center. ex. the centers of my 11" Gemballas are concave so the lips look larger than they would if they were flat (fyi - John from DC has the same rims on his black 993TT and they look awesome on his car).

David in LA

btw, IMHO I think you should go to 9" in the front....that's would I would do if I were to buy new rims

msobota

My upgrade includes K24 turbos modified by Powerhaus with a "Sport Compressor wheel and clipped exhaust wheel" whatever this means. I think it's designed to deliver the power at a lower RPM. With the new turbos, a new chip is necessary. BMC air filter and Bailey Diverter Valves (the Bailey DV's might not have been necessary but they do not cost big bucks).

The upgrade cost $10,000. Add $2000 for the sport oil cooler (Carnewal.com) The power for the dollar is very significant but my upgrade came along with some issues.

My power goes to 500 at the rear wheels at 5000 rpm. This is 120hp better than stock and allows me to walk away from a stock 993tt. Ask John H! The car really goes much better than stock and totally drivable. Then the power starts falling off as the rpms continue up to redline. By the time the rpms are at redline, the power is only 20hp or so better than stock. It is possible that there is some detonation and that the ECU is backing off to compensate. I now have a couple of drums of VP Motorsport 103 racing fuel to work with and get the car back on the dyno. I expect to see the power hold. I plan to do some more work on the issue in February.

My car was modified at Autothority and I regret to inform you that I had a bad experience there.

Keith A. Has a similar upgrade from AWE in Philly using the GIAC chip. If you are on the east coast, you should go to AWE on the 22nd and witness a bunch of power addicts on the dyno. I wish I could be there.

On the west coast there are several possibilities the guys will be happy to tell you about.



Mike Sobota

Norske

I have the same set up on my C$S. I bought hollow sokes that are 8.5 and 11 and the fit fine. I also have the PSS9 and it is great.

Mike W

David, Why do you prefer the 9 to 8.5 up front? Any rubbing issues with the 9s?