I'm getting ready to buy new ruubber for my turbo. I'm going to purchase the GT2 sized rubber (315 30 18 and 235 40 18) to go on HRE 540r's. This will be for the daily driver portion of the car so low noise is more important than sticky rubber. I have the track tires mounted on the original stock wheels.

In the board members opinion what tire brand has the least amount of road noise and what brand has the most grip in the size mentioned above? Thanks for the help.

P.S. Great board guys!

P.S.S. Rayn, your thread was getting too long so.....Congratulations!!!!! I have an office in KC so I'll have to stop by Imagine to watch the progress.

I just put on Michelin Pilot Sports (GT2 sizes) last week , I've only put on a few hundred miles so far but and its MUCH quieter
then the PZeros.

When i changed to the 540r's I went with the Yokos AVS. I dont notice much in terms of road noise but that could be due to the radio being loud. As far as grip goes, I am not sure if i havent "pushed" as hard or if the rubber can just handle everything i throw at it, but regardless I have been very satisfied.

You should ask Chad/CJV about the fitment... You wil probably get rubbing on those rear 315s...

David,

What kind of wheels do you have? Size/Offset?

Given my experience with the GT2 sized Michelins on my car, the ride quality was much better than the standard TT tires. They should also fit fine (no rubbing) assuming the offsets of your new wheels are not too aggressive. To be on the conservative side, stay close to the GT2 wheel specs and you'll have no fitment issues, even with a significantly lowered car. In other words, if you go with GT2 sized wheels (8.5" and 12" wide) keep the offsets of the 540R's as close as possible to the factory GT2 offsets of 40mm and 45mm front and rear, respectively, to avoid any rubbing issues and need to roll fenders. If your rear wheel is only 11.5" wide, you can easily accommodate an offset of 38mm. Hope this makes sense. It may be possible to go a bit more aggressive on the offsets, but rubbing issues may present themselves.

I too am about to switch to 315s and 235s. I currently have HRE 540Rs -- 8s in fronts and 11s in the rear with a 3 in lip. In order to accomodate the larger tires, I am going replace the outers on both the front and rear, such that the rears will be 11.5 with a 3.5 inch lip, and the fronts will be 8.5. HRE has confirmed that, with my present offset (stock), I can accomplish this without rubbing.

I am currently running Michelin Pilot Sport Cups and love them. Therefore, I am waiting until Michelin releases the 235 Cups (315s are currently available) before making the switch. I've been in touch with Doug Brown at Michelin and he indicates that the 235s should be available within 60 days.

BCS996TT they are HRE 540R's 18X8 37 offset and 18X11 57 offset. I don't believe the 315's will rub. It's only 20mm. Not sure about the front though.

Your front combo should work w/o rubbing, but your rear setup seems wrong. A 57mm offset for the 11" wide rear will suck the rear wheel/tire in towards the suspension by approx. 1/2" more than stock. That can't be what you want?? If you're staying with the stock widths, you can go with offsets that are 16 and 12 mm more aggressive (smaller ET #) front and rear, respectively, w/o rubbing using GT2 sized tires.

Jack or Chad,

What about using Stock 996TT offset and Wheel sizes with 315s? Will they fit without any issues?

Yes, the stock 11" wide wheel ET 45 with a 315x30 tire will fit with out any issues. Some might say that a 315 tire would "sit" better on a 11.5" wide wheel, but this has nothing to do with wheel arch clearance.

Jack (LA), I just check with Mike at HRE the rear offset paperwork says 57. He tells me that could be right because HRE typically pushes the wheel right to the well. Anyway here is a picture of the current rears. Do you know of an easy way to measure the clearance. I think all I need is about 10mm more right? Thanks for the help.

An ET of 57 (as compared to the stock Turbo rear offset of 45)pushes the wheel inward not toward the wheel well. The smaller the ET# the more the wheel sticks outward, filling up the wheel well. That's why I'm a bit confused.

You can fit a 315 tire on the 11" wide rear wheel with offsets between 33 and 45 mm. As you approach the 33mm ET, clearance starts to get tight and fender rolling may be required depending on the height of your car.

Although it will fit, Doug Brown at Michelin does not recommend putting 315 Cups on an 11 inch wheel. Rather, he recommends 11.5s or 12s. That being said, I've heard of a number of 996TT/C4S owners who have mounted 315s on 11s without a problem. Personally, I want the larger contact patch achieved by the wider rim.

Richard:

Looking at your picture, it looks like your wheel has an offset closer to the stock offset, maybe it's a 37 rather than a 57. HRE would never make a 57mm offset for a wide body Porsche. But back to your question, the answer is a qualified YES -- it should fit. I have no easy way/method for you to measure whether you will have the extra 10mm inside and outside clearance for the wider 315 tires. Sorry.