Will72

Hi -
Anyone seen this message on their display (PTM Inactive. Too Hot)?
The changes that were made were:
With Stock wheels (2007 997 Turbo)
Hoosier R6 Tires were: F 235 35 19, R 295 30 19
Bilstein PSS10 coilovers with PASM (standard height)

To:
Same Stock Wheels
Hoosier Tires: F 265 35 19, R 315 30 19
Suspension: lowered all the way
Camber plates added (max camber)
Spacers added to the front only (5mm)
Strut tower brace

After pick up from the shop, standard pulling on the regular road (side to side) due to the change in the road surface (ruts and typical road crown).

The message would show up on my center console readout. After a few minutes it would go away. I drove it about 300 miles total (on two different occasions. The message only showed up once each time and after about 20-40 mins of driving.

My dealer (Porsche Annapolis) is looking to Porsche to see if the tire size or the camber could be the issue. I think it has more to do with the lateral acceleration than the difference in tire sizes. Between the stock, starting, and final tires (listed above), there is minimal difference in the actual tire size.

Thanks for any responses.

Will

sparkhill

Tire size is definitely the issue. 315's are well know to cause front differential overheating issues.

Stock sizes are 235/35-9 (80.0 cm circumference) and 305/30-19 (82.3 cm), F/R difference +2.8%. 295/30-19 (81.6 cm) is 0.9% smaller than stock with F/R diff +1.9% and are fine (I use these in the winter)

The tires you are running are 265/35-19 (82.6 cm) and 315/30-19 (83.1 cm). The fronts are 3.2% larger than stock, the rears are 3.8% larger than stock and the F/R difference is 0.5% which is enough to cause your problem. Your dealer should know better. Stop driving the car until you source proper sized tires or you will ruin your differential; such damage is not a warranty item.

Will72

Thanks for the response. It was my speed shop and not the dealer that did this. If I understand you correctly, it's not the difference in size front to rear, but the difference in size in general? So, comparing the original rear to the new rear correct?

If I go to 18" wheels to track the car, what tire will work? Currently Hoosier doesn't make a 305 in 19's for my stock wheels. Any suggestions for a replacement for Hoosier R6's?

Thanks again. I actually had the dealer and shop stumped.

sparkhill

The 997TT is very sensitive and I think both the circumference and the front/rear difference needs to be similar to stock. I think you are fine on the circumference It is just that stock, the rears are have a 2.8% larger circumference than the fronts, the 295's have a 1.9% larger rear circumference than the fronts and your setup has a 0.5% larger rear circumference compared to stock. The rears need to be about 2-3% larger than the fronts.

235/35-19 / 315/30-19 are 3.8% F/R so they do not work.
265/35-19 / 315/30-19 are 0.5% F/R so they do not work.
265/35-19 / 325/30-19 are 1.4% and I think people run these without issue, but I don't know for sure.

http://www.6speedonline.com/forums/9...15s-rears.html

Both 18's or 19's, I would just call Damon@TireRack and order what he recommends.

sparkhill

It looks like Damon recommends 245/35-18 and 295/30-18 if you go with Hoosier R6 18's. see post #7

Will72

So...my problem is resolved. I did call Damon at Tire Rack and he helped. I ended up increasing the size of my rears (325's) and left the fronts as is. This gave the car the needed 2-3% larger rears it had been configured with and whamo, no PTM error.
While on the phone I went ahead and purchased an extra set of wheels/tires. I went with OZ's and 255 35 18 (F) and 335 30 18 (R).

I purchased black wheels and Tire Rack didn't have center caps that matched (Black with colored Porsche emblem) so Damon recommended I call Wheel Enhancement. They had the center caps I needed. David Martin helped me and was very helpful. The center caps were 80 bucks each. I felt it was a bit expensive (and it is). When I got them they were plastic and one was damaged slightly leaving the white plastic exposed. Nothing a little sharpie (marker) couldn't fix though... So, with shipping, my caps came to 350 bucks. They match and look good which I guess is the price you have to pay.

Cheers. First track event this weekend at VIR.

jason952

997TT is a lot of car for a first track event. good luck

TT Surgeon

I think he means first event of the season....