mikymu

Thanks Joe

Hope we can meet someday - perhaps Laguna if you ever venture up this way. Enjoy your GT3

Mike

mkozink

The crack is the tread splice line as I described. It is "perpendicular" to the direction of the tread. If you can see the carcass of the tire then it should not be used as you have already surmised.

iLLM3

Agreed, that tire is shot , do not use it!

deputydog95

Any issues with the NT01's related to the shorter diameter and ABS, etc? They come in about an inch shorter from and rear in those sizes vs stock, right?

mdrums

Dog, after we spoke I checked out the sizes the NT01's come in and the raer 315-30-18 will be fine but the fronts will be taller with a 235. The other size is a 275 and I do not think those will fit a GT3. The stock diameter is larger is the rear than the front and with the NT01's this will be backwards. Not sure how this might affect ABS ect....

deputydog95

This is from Nitto's site... Why is this co complicated????

deputydog95

The 245 and 315 are within .2 inches of each other, with the fronts being .2 inch taller than the rears. Does it matter?

mdrums

That is what I would like to find out.

Stock 19's diameter are :
235-35-19 diameter: 25.5
305-30-19 diameter: 26.3

The 18's I run and other run on 997 GT3's and Carrera S cars are:

same as stock but in 18"
245-40-18 diameter :25.7
305-35-18 diameter: 26.3

smaller than stock but still the rears are bigger diameter
255-35-18 diameter 25.1
315-30-18 diameter 25.5

AllanJ

Try this guys:

Stock front to rear diameter ratio:
25.5 / 26.3 = 0.9696

So what you want from other combos is a ratio that is 0.9696 +/- 3%. This works out to be 0.9696 +/- 0.0291.

This is: 0.9405 to 0.9987

So you want the front diameter divided by the rear diameter to be between 0.9405 and 0.9987

From the example above:
same as stock but in 18"
245-40-18 diameter :25.7
305-35-18 diameter: 26.3

25.7 / 26.3 = 0.9771 <-- definitely in range

The other example:
smaller than stock but still the rears are bigger diameter
255-35-18 diameter 25.1
315-30-18 diameter 25.5

25.1 / 25.5 = 0.9843 <-- still in range

You're good.

The Nittos mentioned above don't fit in the 3% tolerance so it can be a bit sketchy. Not sure what the factory tolerance really is. The front 235/40 might work with the 315..... maybe. The 245 has less of a chance. Try it and let the gang know.

Cheers,

deputydog95

Referencing the max range of 0.9405 and 0.9987 on the stock setup....

On the nitto combo of 315 and 245, I come up with 1.008 (0.0093 over the max)

On the nitto combo of 315 and 235, I come up with 1.002 (0.0033 over the max)

That's pretty damn close to the top end of the range. I wonder if its enough to cause a problem?

How much of an issue is it that the stock 19" tire combo has a .8 larger rear? Should whatever tire combo we go with maintain a slightly taller rear as well. Or does it even matter? Both nittos are slightly taller in the front than the rear.

AllanJ

I dunno. It depends on what the actual value is for the tolerance in the ABS computer. Also keep in mind the rear tires wear about 2x as fast as the fronts. The overall diameter of the rear will shrink faster then the front as time goes on.

Ideally, yes. Keeps the ratio under 1.0 which is closer to the oem range, but I don't have accurate info on the factory tolerance. It might be (barely) ok.

deputydog95

This is causing me to do way too much math. I guess I'll just get the 888's

AllanJ

Too bad......R888 suck.

deputydog95

Unfortunately my options in 19" wheels are not good. Corsas are crazy $$$. Sport Cups in 19" from what I understand are not as good as the 18"s and are also sick money.

All I'm left with are 888's. Guess I better learn how to drive on them

mdrums

888's are not as bad as some will try to have you believe. They do heat cycle out faster than RA1's....but full tread R888's are better than full tread RA1's. To really use RA1's you will need to either put up with mushy feeling tires for 2-3 DE's or have the RA1's shaved to 5'32nds but then after 2-3 DE's the RA1's will be worn down to basically slicks. At that point they will feel awesome on the track but driving home in the afternoon rain (it's Florida) you will hate the RA1's on the street. With the R888's you can drive them at full tread and have a decent tire with tread to drive home on in the rain.

For driving to and from the track you get about as much life out of RA1's and R888's (maybe more with the R888) because on the street you will not be able to drive the RA1's when the tread blocks are worn down.

So either get a trailer and use RA1's or Hoosiers or get R888's to drive to and from the track and live with them when they start to heat cycle out some but still have tread for the rain.