My 2001 996TT is lowered appr. 1 1/2" on PSS9's. I currently run OEM 8" and 11" wheels on the track with Hoosier R6 315/30-18 and 245/40-18 on the track. I believe the Boxter 18x9" rear wheels with 43mm offset should fit up front, allowing me to use Hoosier R6 255/35-18. They are actually about 1" wider than the 245's. Has anyone tried this combination, and does it fit?
I have already moved my radiators forward to fit the 245/40's. The clearance to the strut looks ok but I amy hit the inside in the front and the back of the fenderliner on the outside. Also, when trying the wheel for clearance I was able to compress the strut some, but not enough to check fender clearance.

 

i run boxster 18 9 43mm with 235 40 18 wheels
coilovers 1.5 lowered. small camber ...-.9 only
no rubbing perfect fit.

 

strut clearance with coils is fine. I'm very close to front fenderliner though when turning.

 

This wheel combination is kinda weird (315/30 and 245/40). Dont you have problems with your visco clutch/4wd? Any ABS/ESP problems? As far as i know only the combination 225/40 and 295/30 or 315/25 works and is allowed.
And your speedometer should not go right and needs a calibration.

 

olwe

I see you moved your radiators forward. I just posted requesting help on this topic.

Hoping you can respond to my thread.

I'm interested in hearing if you are successful fitting that tire / wheel combo.

 

If anyone knows of a set of Boxter 18x9x43mm rears - scratched is ok - pls let me know.

I have ordered a set of R6 255/35-18 and will keep the group posted on the outcome.

Diameters should be ok. According to Hoosier's catalog the diameters are 24.8 front and 25.6 rear; a difference of 2.5%. My calculator brings it even closer.

 

As long as you are within an inch you are ok. I have run the 315 and 255/35 quite a bit (like the 245 better though). It does require some setup change compared to a 245, the car will be much more tail happy.

No idea on the wheels.

 

why are you guys moving radiators, the tire fits just fine.

 

My 245/40-18 R6's on stock wheels hit the radiators hard. There was no option.

Ola

 

we lug wheels

 

Thats odd I ran 255's and I know guys ran 265's on fronts and no rubbing ..

 

Providing an update after my first run on new tire/wheel/rotor combo.
Re-iterating: 2001 996TT lowered appr. 1 1/2" on PSS9's. For track I use stock wheels in rear with 315/30-18 Hoosier R6. I just switched to 255/35-18 on Cayman rear wheels 18x9, 43mm offset, and Girodisc rotors. Camber is 1.3 deg. front on stock lower arms and 2.0 deg. in rear.
Comments:
Wheel fit is perfect. Strut clearance with this wheel was very close to that with stock wheels.
Slight re-shaping of front fenderliners was needed at the rear (easy with a heat gun). My front radiators were already moved, and the fenderliners re-shaped, to fit 245/40-18. Clearance in front is greater with the smaller 255/35.
Fenders were pushed out very slightly (appr. 8mm) to clear the tire. This was easily done with a fender rolling tool, without paint cracking.
Result: Handling greatly improved with wider front tires. No rubbing in front. Rear tires still rub the liners under heavy compression (top outside) and when the rear lifts (by intercooler hoses).
Brakes: Sebring is very hard on brakes. I have always eventually put my foot on the floor in the past at Sebring. Girodisc 350 mm rotors all around with PFC pads, titanium backing plates behind the pads, Suncoast large front scoops (larger than GT2), and Motul 660 allowed me to run the track with confidence. No problems in over 200 Sebring track miles.

 

sounds like a very solid setup. it seems there is just no way around that full compression momentary wheel rub in the rear if ever wider than oem. that's where my wear/rub marks are too.

 

What was the aspect ratio? How tall were they?

 

One more comment to add:
This tire combination, 255/35 and 315/30-18, should only differ in diameter by .4". However, Hoosier's catalog show them as differing by 0.8" and I measure about 0.7". 0.8" equates to 3.2% difference in circumference and is enough to make the PSM activate even on straights under full power. Driving with PSM off all symptoms go away. Hopefully I am not killing my front to rear diff too quickly.