+1... I've got the same model car as you.

My (pre-owned) car came with 235/35/19's and 305/30/19's and from reading these threads, my ratio of front-to-rear diameter is too great.

 

hey doc, i put stock 997 turbo wheels and tires on my 04 turbo with no issues at all. that was 6000 miles ago. put them on and enjoy...........

 

Thanks guys, Turbo Turbo, did you get any rubbing at all? Any need for spacers? So many people say so many different things on every tread I read here and on Rennlist, I really don't know what to think. I have a friend that installed 997.2 tt wheels on his 02 996 tt. He has a little rubbing, but no other issues in almost 2 years.

 

They will fit...but remember the most important thing on a 996 Turbo is the overall diameter between the front and rears. They have to be almost exactly the same (about 2% difference max).

I think the 19" wheels are good for the street, but stick to stock sizes on the track...your car is built for 'em.

 

So what % diferential would the stock 997 tt wheels/ tires have?

 

doc, just put them on, no spacers, no rubbing, no nothing........ just put them on and goooooooooooo.

 

Stock 997TT **TIRE** sizes are wrong for the 996TT.

Some people claim to have no issues- perhaps their diffs have failed 'silently'? Others fail with noise and symptoms?

But clearly the mismatch exceeds the stock set up.

Forget people with the "1% and 2%" criteria...look at the mismatch in "revs/mile". Stock mismatch is THREE. if you triple that mismatch to 9, you are dissipating 3 times the energy.

 

A couple cars I test drove with 997TT wheels had a noticeably harsher ride, I fail to see the benefits.

 

I have the 997tt tires on my 02 996tt coupe. There are two concerns: (1) height of the tire and (2) front and rears being close in height so as not to cause your diff to overheat and break.

The specs you are supposed to conform to for this setup:

1. Height (aka diameter of tire) is not supposed to be over 25.5'' tall. Anything taller than this and you risk rubbing on the inside wheel arches, at least without spacers you do. I have not used spacers. The problem with stock 997tt tire sizes is that they are too tall. 295/30/19 is 26.0'' tall and 305/30/19 is 26.3'' tall. There are at least two reports or more of people with this setup with at least slight rubbing.

2. Ratio between front and rear tires: The 996tt is not an electromagnetic diff like the 997tt is, its a viscous diff with lower tollerances, so the front tires and back tires need to be within .3 inches of each other. Sure, you can go over this, but you will overheat the diff and will eventually have a problem. Here is a relevant thread: https://www.6speedonline.com/forums/...ire-se-up.html

Solution: The best setup for 997tt wheels on a 996tt are:

Front: 225/35/19 - 25.2'' diameter, so same revs and height
Rear: 315/25/19 - 25.2'' diameter, perfect match for front

Also supposedly ok is the stock 997tt FRONT wheel size at 235/35/19 with 315/25/19 becuase they are 25.5'' diameter which is right at the max height and within .3'' ratio to rears. This is what I have on my car currently, but I've also had some PSM activation issues around high speed corners which may or may not be related. (see next post).

Unfortuantey, the above are the ONLY two potential setups I think that can be "recommended." You will basically always need 315/25/19 on the rears, and that really sucks b/c there is a very limited selection in that size and they are very pricey. Tire rack only has them in PS2's for $540 each. I put on Nitto Invos at $360 each from ebay on in 315/25/19 . You can also get Falkens for a little more $. I wish Hankook make thier V12 Ventus in that size. With the 996tt's aggressive camber setup, they all will be worn on the inside in about 10k miles with fairly aggressive street driving, and I don't track or notice a meaningful difference to my driving fun with PS2's vs cheaper max performance alternatives.

 

The benefit is that they look fantastic and really update the car. It's like putting F430 wheels on a 360 modena. Most people can't even tell it's the older model still. Every single time I look at my car, I notice how fantastic the 997tt wheels look on it.

But you are right wrt to ride. I didnt' really experience a more harsh ride, but it was definately more darty. I also have had pretty consistent PSM activation problems around fast turns since putting them on 18 months ago. I have mismatched tires (PS2's 235/35/19 that came with the rims on a 997tt and I put Nitto Invos 315/25/19 on the rear wheels to be within spec as I mentioned above). I've had no rubbing. I've reset the steering angle sensor, but not sure what else to do wrt to the PSM issue. It's not a big deal since it only seems to come on long, high speed corners, but it has been annoying and is very unsettling when it occurs, especially without a two hand grip on the wheel. I'm planning to put Hankook V12 Ventus tires at 225/35/19 on the front in a couple months, and also get it aligned again (which is likely the darty problem and perhaps the PSM problem too) and that will fix it since ride height will be an exact match between front and rear, despite mismatched brands again. I just couldn't resist getting the Hankooks to try b/c i got them with a cashback/special offer new for about $90 each.

 

Does any body want to buy a set of 997 tt wheels with almost new Michelin on the stock sizes? I am not taking any chances and I don't want to buy new tires. I just got new tires for my stock 18" less than 3,000 k ago.

 

This was recently posted by someone. I'm on my phone so I just copied and pasted.


Hey folks,

As of last Thursday, I'm a new owner of a Lapis 996 TT. Love the way the car drives - it doesn't stop blowing my mind every minute.

Except. This :

https://skydrive.live.com/redir.aspx...!iyaBVxDoac%24

At the 3 second mark, you can hear me blip the throttle to get from 6th to 4th. The engine is barely audible. I then accelerate a little bit and then at the 7 second mark I shift to neutral. Then at the 14 second mark, I blip the throttle while in neutral. The wheel-speed-dependent drone is very very obvious in this video.

I bought the car in Dallas from RAC Performance and am on a road trip back to Seattle where I live. I'm currently in Albuquerque and don't think I should be driving the car anymore. Needless to say, I'm a bit stranded.

Any thoughts on what could be the culprit and what I should do here? I don't think it's wheel bearings - the noise does not really change appreciably if I turn one direction or the other. A friend in ABQ and I put the car up on stands and did a quick look-around. The wheels are tight. And if you rotate the front wheels be hand, there does seem to be noise coming from the center line of the car. Bad diff maybe?

All ideas welcome at this point. Please help me get home with the new car safely!

 

If you got the 997tt wheels for a good price, you might consider selling just the tires in the parts section here, as well as the 996tt wheels with good tires (lots of people want those to track). I'd think you could get $700 or more for the 996tt wheels/tires, and another $350-$600 for your 997tt Michelins tires, so you'd net well over a grand to put some proper sized, fresh rubbers on the 997tt wheels.

Of course, I'm not promising you that it'll work out perfectly, but its a common mod and only a few people have the PSM issue I got or any other problems with right tire sizes. They certainly really update the car.

 

Beautiful Lift . Where did you buy it from ?

 

Anyone done this recently? I just acquired a set of these wheels and am a little concerned about getting the right size tires. Any suggestions from what is currently available?

Thanks!